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translation: Add Python and Java code for EN version (#1345)
* Add the intial translation of code of all the languages * test * revert * Remove * Add Python and Java code for EN version
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Yudong Jin
117
en/codes/java/chapter_graph/graph_adjacency_list.java
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117
en/codes/java/chapter_graph/graph_adjacency_list.java
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/**
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* File: graph_adjacency_list.java
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* Created Time: 2023-01-26
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* Author: krahets (krahets@163.com)
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*/
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package chapter_graph;
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import java.util.*;
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import utils.*;
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/* Undirected graph class based on adjacency list */
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class GraphAdjList {
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// Adjacency list, key: vertex, value: all adjacent vertices of that vertex
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Map<Vertex, List<Vertex>> adjList;
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/* Constructor */
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public GraphAdjList(Vertex[][] edges) {
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this.adjList = new HashMap<>();
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// Add all vertices and edges
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for (Vertex[] edge : edges) {
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addVertex(edge[0]);
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addVertex(edge[1]);
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addEdge(edge[0], edge[1]);
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}
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}
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/* Get the number of vertices */
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public int size() {
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return adjList.size();
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}
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/* Add edge */
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public void addEdge(Vertex vet1, Vertex vet2) {
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if (!adjList.containsKey(vet1) || !adjList.containsKey(vet2) || vet1 == vet2)
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throw new IllegalArgumentException();
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// Add edge vet1 - vet2
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adjList.get(vet1).add(vet2);
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adjList.get(vet2).add(vet1);
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}
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/* Remove edge */
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public void removeEdge(Vertex vet1, Vertex vet2) {
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if (!adjList.containsKey(vet1) || !adjList.containsKey(vet2) || vet1 == vet2)
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throw new IllegalArgumentException();
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// Remove edge vet1 - vet2
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adjList.get(vet1).remove(vet2);
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adjList.get(vet2).remove(vet1);
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}
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/* Add vertex */
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public void addVertex(Vertex vet) {
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if (adjList.containsKey(vet))
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return;
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// Add a new linked list to the adjacency list
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adjList.put(vet, new ArrayList<>());
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}
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/* Remove vertex */
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public void removeVertex(Vertex vet) {
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if (!adjList.containsKey(vet))
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throw new IllegalArgumentException();
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// Remove the vertex vet's corresponding linked list from the adjacency list
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adjList.remove(vet);
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// Traverse other vertices' linked lists, removing all edges containing vet
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for (List<Vertex> list : adjList.values()) {
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list.remove(vet);
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}
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}
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/* Print the adjacency list */
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public void print() {
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System.out.println("Adjacency list =");
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for (Map.Entry<Vertex, List<Vertex>> pair : adjList.entrySet()) {
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List<Integer> tmp = new ArrayList<>();
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for (Vertex vertex : pair.getValue())
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tmp.add(vertex.val);
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System.out.println(pair.getKey().val + ": " + tmp + ",");
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}
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}
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}
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public class graph_adjacency_list {
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public static void main(String[] args) {
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/* Initialize undirected graph */
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Vertex[] v = Vertex.valsToVets(new int[] { 1, 3, 2, 5, 4 });
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Vertex[][] edges = { { v[0], v[1] }, { v[0], v[3] }, { v[1], v[2] },
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{ v[2], v[3] }, { v[2], v[4] }, { v[3], v[4] } };
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GraphAdjList graph = new GraphAdjList(edges);
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System.out.println("\nAfter initialization, the graph is");
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graph.print();
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/* Add edge */
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// Vertices 1, 2 i.e., v[0], v[2]
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graph.addEdge(v[0], v[2]);
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System.out.println("\nAfter adding edge 1-2, the graph is");
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graph.print();
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/* Remove edge */
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// Vertices 1, 3 i.e., v[0], v[1]
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graph.removeEdge(v[0], v[1]);
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System.out.println("\nAfter removing edge 1-3, the graph is");
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graph.print();
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/* Add vertex */
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Vertex v5 = new Vertex(6);
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graph.addVertex(v5);
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System.out.println("\nAfter adding vertex 6, the graph is");
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graph.print();
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/* Remove vertex */
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// Vertex 3 i.e., v[1]
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graph.removeVertex(v[1]);
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System.out.println("\nAfter removing vertex 3, the graph is");
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graph.print();
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}
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}
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131
en/codes/java/chapter_graph/graph_adjacency_matrix.java
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131
en/codes/java/chapter_graph/graph_adjacency_matrix.java
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/**
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* File: graph_adjacency_matrix.java
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* Created Time: 2023-01-26
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* Author: krahets (krahets@163.com)
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*/
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package chapter_graph;
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import utils.*;
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import java.util.*;
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/* Undirected graph class based on adjacency matrix */
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class GraphAdjMat {
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List<Integer> vertices; // Vertex list, elements represent "vertex value", index represents "vertex index"
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List<List<Integer>> adjMat; // Adjacency matrix, row and column indices correspond to "vertex index"
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/* Constructor */
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public GraphAdjMat(int[] vertices, int[][] edges) {
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this.vertices = new ArrayList<>();
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this.adjMat = new ArrayList<>();
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// Add vertex
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for (int val : vertices) {
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addVertex(val);
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}
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// Add edge
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// Please note, edges elements represent vertex indices, corresponding to vertices elements indices
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for (int[] e : edges) {
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addEdge(e[0], e[1]);
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}
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}
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/* Get the number of vertices */
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public int size() {
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return vertices.size();
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}
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/* Add vertex */
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public void addVertex(int val) {
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int n = size();
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// Add new vertex value to the vertex list
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vertices.add(val);
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// Add a row to the adjacency matrix
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List<Integer> newRow = new ArrayList<>(n);
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for (int j = 0; j < n; j++) {
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newRow.add(0);
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}
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adjMat.add(newRow);
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// Add a column to the adjacency matrix
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for (List<Integer> row : adjMat) {
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row.add(0);
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}
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}
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/* Remove vertex */
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public void removeVertex(int index) {
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if (index >= size())
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throw new IndexOutOfBoundsException();
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// Remove vertex at `index` from the vertex list
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vertices.remove(index);
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// Remove the row at `index` from the adjacency matrix
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adjMat.remove(index);
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// Remove the column at `index` from the adjacency matrix
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for (List<Integer> row : adjMat) {
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row.remove(index);
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}
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}
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/* Add edge */
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// Parameters i, j correspond to vertices element indices
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public void addEdge(int i, int j) {
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// Handle index out of bounds and equality
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if (i < 0 || j < 0 || i >= size() || j >= size() || i == j)
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throw new IndexOutOfBoundsException();
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// In an undirected graph, the adjacency matrix is symmetric about the main diagonal, i.e., satisfies (i, j) == (j, i)
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adjMat.get(i).set(j, 1);
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adjMat.get(j).set(i, 1);
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}
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/* Remove edge */
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// Parameters i, j correspond to vertices element indices
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public void removeEdge(int i, int j) {
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// Handle index out of bounds and equality
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if (i < 0 || j < 0 || i >= size() || j >= size() || i == j)
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throw new IndexOutOfBoundsException();
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adjMat.get(i).set(j, 0);
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adjMat.get(j).set(i, 0);
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}
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/* Print adjacency matrix */
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public void print() {
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System.out.print("Vertex list = ");
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System.out.println(vertices);
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System.out.println("Adjacency matrix =");
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PrintUtil.printMatrix(adjMat);
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}
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}
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public class graph_adjacency_matrix {
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public static void main(String[] args) {
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/* Initialize undirected graph */
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// Please note, edges elements represent vertex indices, corresponding to vertices elements indices
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int[] vertices = { 1, 3, 2, 5, 4 };
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int[][] edges = { { 0, 1 }, { 0, 3 }, { 1, 2 }, { 2, 3 }, { 2, 4 }, { 3, 4 } };
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GraphAdjMat graph = new GraphAdjMat(vertices, edges);
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System.out.println("\nAfter initialization, the graph is");
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graph.print();
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/* Add edge */
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// Indices of vertices 1, 2 are 0, 2 respectively
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graph.addEdge(0, 2);
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System.out.println("\nAfter adding edge 1-2, the graph is");
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graph.print();
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/* Remove edge */
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// Indices of vertices 1, 3 are 0, 1 respectively
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graph.removeEdge(0, 1);
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System.out.println("\nAfter removing edge 1-3, the graph is");
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graph.print();
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/* Add vertex */
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graph.addVertex(6);
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System.out.println("\nAfter adding vertex 6, the graph is");
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graph.print();
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/* Remove vertex */
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// Index of vertex 3 is 1
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graph.removeVertex(1);
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System.out.println("\nAfter removing vertex 3, the graph is");
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graph.print();
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}
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}
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55
en/codes/java/chapter_graph/graph_bfs.java
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55
en/codes/java/chapter_graph/graph_bfs.java
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/**
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* File: graph_bfs.java
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* Created Time: 2023-02-12
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* Author: krahets (krahets@163.com)
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*/
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package chapter_graph;
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import java.util.*;
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import utils.*;
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public class graph_bfs {
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/* Breadth-first traversal */
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// Use adjacency list to represent the graph, to obtain all adjacent vertices of a specified vertex
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static List<Vertex> graphBFS(GraphAdjList graph, Vertex startVet) {
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// Vertex traversal sequence
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List<Vertex> res = new ArrayList<>();
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// Hash set, used to record visited vertices
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Set<Vertex> visited = new HashSet<>();
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visited.add(startVet);
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// Queue used to implement BFS
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Queue<Vertex> que = new LinkedList<>();
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que.offer(startVet);
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// Starting from vertex vet, loop until all vertices are visited
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while (!que.isEmpty()) {
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Vertex vet = que.poll(); // Dequeue the vertex at the head of the queue
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res.add(vet); // Record visited vertex
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// Traverse all adjacent vertices of that vertex
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for (Vertex adjVet : graph.adjList.get(vet)) {
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if (visited.contains(adjVet))
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continue; // Skip already visited vertices
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que.offer(adjVet); // Only enqueue unvisited vertices
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visited.add(adjVet); // Mark the vertex as visited
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}
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}
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// Return the vertex traversal sequence
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return res;
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}
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public static void main(String[] args) {
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/* Initialize undirected graph */
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Vertex[] v = Vertex.valsToVets(new int[] { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 });
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Vertex[][] edges = { { v[0], v[1] }, { v[0], v[3] }, { v[1], v[2] }, { v[1], v[4] },
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{ v[2], v[5] }, { v[3], v[4] }, { v[3], v[6] }, { v[4], v[5] },
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{ v[4], v[7] }, { v[5], v[8] }, { v[6], v[7] }, { v[7], v[8] } };
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GraphAdjList graph = new GraphAdjList(edges);
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System.out.println("\nAfter initialization, the graph is");
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graph.print();
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/* Breadth-first traversal */
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List<Vertex> res = graphBFS(graph, v[0]);
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System.out.println("\nBreadth-first traversal (BFS) vertex sequence is");
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System.out.println(Vertex.vetsToVals(res));
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}
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}
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51
en/codes/java/chapter_graph/graph_dfs.java
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51
en/codes/java/chapter_graph/graph_dfs.java
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/**
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* File: graph_dfs.java
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* Created Time: 2023-02-12
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* Author: krahets (krahets@163.com)
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*/
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package chapter_graph;
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import java.util.*;
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import utils.*;
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public class graph_dfs {
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/* Depth-first traversal helper function */
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static void dfs(GraphAdjList graph, Set<Vertex> visited, List<Vertex> res, Vertex vet) {
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res.add(vet); // Record visited vertex
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visited.add(vet); // Mark the vertex as visited
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// Traverse all adjacent vertices of that vertex
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for (Vertex adjVet : graph.adjList.get(vet)) {
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if (visited.contains(adjVet))
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continue; // Skip already visited vertices
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// Recursively visit adjacent vertices
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dfs(graph, visited, res, adjVet);
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}
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}
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/* Depth-first traversal */
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// Use adjacency list to represent the graph, to obtain all adjacent vertices of a specified vertex
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static List<Vertex> graphDFS(GraphAdjList graph, Vertex startVet) {
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// Vertex traversal sequence
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List<Vertex> res = new ArrayList<>();
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// Hash set, used to record visited vertices
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Set<Vertex> visited = new HashSet<>();
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dfs(graph, visited, res, startVet);
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return res;
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}
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public static void main(String[] args) {
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/* Initialize undirected graph */
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Vertex[] v = Vertex.valsToVets(new int[] { 0, 1, 2, 3, 4, 5, 6 });
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Vertex[][] edges = { { v[0], v[1] }, { v[0], v[3] }, { v[1], v[2] },
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{ v[2], v[5] }, { v[4], v[5] }, { v[5], v[6] } };
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GraphAdjList graph = new GraphAdjList(edges);
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System.out.println("\nAfter initialization, the graph is");
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graph.print();
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/* Depth-first traversal */
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List<Vertex> res = graphDFS(graph, v[0]);
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System.out.println("\nDepth-first traversal (DFS) vertex sequence is");
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System.out.println(Vertex.vetsToVals(res));
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}
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}
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