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
2026-04-13 18:00:18 +08:00 · 2024-05-06 05:21:51 +08:00
parent b5e198db7d
commit 1c0f350ad6
174 changed files with 12349 additions and 0 deletions
--- a/en/codes/java/chapter_backtracking/n_queens.java
+++ b/en/codes/java/chapter_backtracking/n_queens.java
@@ -0,0 +1,77 @@
+/**
+ * File: n_queens.java
+ * Created Time: 2023-05-04
+ * Author: krahets (krahets@163.com)
+ */
+
+package chapter_backtracking;
+
+import java.util.*;
+
+public class n_queens {
+    /* Backtracking algorithm: n queens */
+    public static void backtrack(int row, int n, List<List<String>> state, List<List<List<String>>> res,
+            boolean[] cols, boolean[] diags1, boolean[] diags2) {
+        // When all rows are placed, record the solution
+        if (row == n) {
+            List<List<String>> copyState = new ArrayList<>();
+            for (List<String> sRow : state) {
+                copyState.add(new ArrayList<>(sRow));
+            }
+            res.add(copyState);
+            return;
+        }
+        // Traverse all columns
+        for (int col = 0; col < n; col++) {
+            // Calculate the main and minor diagonals corresponding to the cell
+            int diag1 = row - col + n - 1;
+            int diag2 = row + col;
+            // Pruning: do not allow queens on the column, main diagonal, or minor diagonal of the cell
+            if (!cols[col] && !diags1[diag1] && !diags2[diag2]) {
+                // Attempt: place the queen in the cell
+                state.get(row).set(col, "Q");
+                cols[col] = diags1[diag1] = diags2[diag2] = true;
+                // Place the next row
+                backtrack(row + 1, n, state, res, cols, diags1, diags2);
+                // Retract: restore the cell to an empty spot
+                state.get(row).set(col, "#");
+                cols[col] = diags1[diag1] = diags2[diag2] = false;
+            }
+        }
+    }
+
+    /* Solve n queens */
+    public static List<List<List<String>>> nQueens(int n) {
+        // Initialize an n*n size chessboard, where 'Q' represents the queen and '#' represents an empty spot
+        List<List<String>> state = new ArrayList<>();
+        for (int i = 0; i < n; i++) {
+            List<String> row = new ArrayList<>();
+            for (int j = 0; j < n; j++) {
+                row.add("#");
+            }
+            state.add(row);
+        }
+        boolean[] cols = new boolean[n]; // Record columns with queens
+        boolean[] diags1 = new boolean[2 * n - 1]; // Record main diagonals with queens
+        boolean[] diags2 = new boolean[2 * n - 1]; // Record minor diagonals with queens
+        List<List<List<String>>> res = new ArrayList<>();
+
+        backtrack(0, n, state, res, cols, diags1, diags2);
+
+        return res;
+    }
+
+    public static void main(String[] args) {
+        int n = 4;
+        List<List<List<String>>> res = nQueens(n);
+
+        System.out.println("Input the dimensions of the chessboard as " + n);
+        System.out.println("Total number of queen placement solutions = " + res.size());
+        for (List<List<String>> state : res) {
+            System.out.println("--------------------");
+            for (List<String> row : state) {
+                System.out.println(row);
+            }
+        }
+    }
+}
--- a/en/codes/java/chapter_backtracking/permutations_i.java
+++ b/en/codes/java/chapter_backtracking/permutations_i.java
@@ -0,0 +1,51 @@
+/**
+ * File: permutations_i.java
+ * Created Time: 2023-04-24
+ * Author: krahets (krahets@163.com)
+ */
+
+package chapter_backtracking;
+
+import java.util.*;
+
+public class permutations_i {
+    /* Backtracking algorithm: Permutation I */
+    public static void backtrack(List<Integer> state, int[] choices, boolean[] selected, List<List<Integer>> res) {
+        // When the state length equals the number of elements, record the solution
+        if (state.size() == choices.length) {
+            res.add(new ArrayList<Integer>(state));
+            return;
+        }
+        // Traverse all choices
+        for (int i = 0; i < choices.length; i++) {
+            int choice = choices[i];
+            // Pruning: do not allow repeated selection of elements
+            if (!selected[i]) {
+                // Attempt: make a choice, update the state
+                selected[i] = true;
+                state.add(choice);
+                // Proceed to the next round of selection
+                backtrack(state, choices, selected, res);
+                // Retract: undo the choice, restore to the previous state
+                selected[i] = false;
+                state.remove(state.size() - 1);
+            }
+        }
+    }
+
+    /* Permutation I */
+    static List<List<Integer>> permutationsI(int[] nums) {
+        List<List<Integer>> res = new ArrayList<List<Integer>>();
+        backtrack(new ArrayList<Integer>(), nums, new boolean[nums.length], res);
+        return res;
+    }
+
+    public static void main(String[] args) {
+        int[] nums = { 1, 2, 3 };
+
+        List<List<Integer>> res = permutationsI(nums);
+
+        System.out.println("Input array nums = " + Arrays.toString(nums));
+        System.out.println("All permutations res = " + res);
+    }
+}
--- a/en/codes/java/chapter_backtracking/permutations_ii.java
+++ b/en/codes/java/chapter_backtracking/permutations_ii.java
@@ -0,0 +1,53 @@
+/**
+ * File: permutations_ii.java
+ * Created Time: 2023-04-24
+ * Author: krahets (krahets@163.com)
+ */
+
+package chapter_backtracking;
+
+import java.util.*;
+
+public class permutations_ii {
+    /* Backtracking algorithm: Permutation II */
+    static void backtrack(List<Integer> state, int[] choices, boolean[] selected, List<List<Integer>> res) {
+        // When the state length equals the number of elements, record the solution
+        if (state.size() == choices.length) {
+            res.add(new ArrayList<Integer>(state));
+            return;
+        }
+        // Traverse all choices
+        Set<Integer> duplicated = new HashSet<Integer>();
+        for (int i = 0; i < choices.length; i++) {
+            int choice = choices[i];
+            // Pruning: do not allow repeated selection of elements and do not allow repeated selection of equal elements
+            if (!selected[i] && !duplicated.contains(choice)) {
+                // Attempt: make a choice, update the state
+                duplicated.add(choice); // Record selected element values
+                selected[i] = true;
+                state.add(choice);
+                // Proceed to the next round of selection
+                backtrack(state, choices, selected, res);
+                // Retract: undo the choice, restore to the previous state
+                selected[i] = false;
+                state.remove(state.size() - 1);
+            }
+        }
+    }
+
+    /* Permutation II */
+    static List<List<Integer>> permutationsII(int[] nums) {
+        List<List<Integer>> res = new ArrayList<List<Integer>>();
+        backtrack(new ArrayList<Integer>(), nums, new boolean[nums.length], res);
+        return res;
+    }
+
+    public static void main(String[] args) {
+        int[] nums = { 1, 2, 2 };
+
+        List<List<Integer>> res = permutationsII(nums);
+
+        System.out.println("Input array nums = " + Arrays.toString(nums));
+        System.out.println("All permutations res = " + res);
+    }
+}
--- a/en/codes/java/chapter_backtracking/preorder_traversal_i_compact.java
+++ b/en/codes/java/chapter_backtracking/preorder_traversal_i_compact.java
@@ -0,0 +1,44 @@
+/**
+ * File: preorder_traversal_i_compact.java
+ * Created Time: 2023-04-16
+ * Author: krahets (krahets@163.com)
+ */
+
+package chapter_backtracking;
+
+import utils.*;
+import java.util.*;
+
+public class preorder_traversal_i_compact {
+    static List<TreeNode> res;
+
+    /* Pre-order traversal: Example one */
+    static void preOrder(TreeNode root) {
+        if (root == null) {
+            return;
+        }
+        if (root.val == 7) {
+            // Record solution
+            res.add(root);
+        }
+        preOrder(root.left);
+        preOrder(root.right);
+    }
+
+    public static void main(String[] args) {
+        TreeNode root = TreeNode.listToTree(Arrays.asList(1, 7, 3, 4, 5, 6, 7));
+        System.out.println("\nInitialize binary tree");
+        PrintUtil.printTree(root);
+
+        // Pre-order traversal
+        res = new ArrayList<>();
+        preOrder(root);
+
+        System.out.println("\nOutput all nodes with value 7");
+        List<Integer> vals = new ArrayList<>();
+        for (TreeNode node : res) {
+            vals.add(node.val);
+        }
+        System.out.println(vals);
+    }
+}
--- a/en/codes/java/chapter_backtracking/preorder_traversal_ii_compact.java
+++ b/en/codes/java/chapter_backtracking/preorder_traversal_ii_compact.java
@@ -0,0 +1,52 @@
+/**
+ * File: preorder_traversal_ii_compact.java
+ * Created Time: 2023-04-16
+ * Author: krahets (krahets@163.com)
+ */
+
+package chapter_backtracking;
+
+import utils.*;
+import java.util.*;
+
+public class preorder_traversal_ii_compact {
+    static List<TreeNode> path;
+    static List<List<TreeNode>> res;
+
+    /* Pre-order traversal: Example two */
+    static void preOrder(TreeNode root) {
+        if (root == null) {
+            return;
+        }
+        // Attempt
+        path.add(root);
+        if (root.val == 7) {
+            // Record solution
+            res.add(new ArrayList<>(path));
+        }
+        preOrder(root.left);
+        preOrder(root.right);
+        // Retract
+        path.remove(path.size() - 1);
+    }
+
+    public static void main(String[] args) {
+        TreeNode root = TreeNode.listToTree(Arrays.asList(1, 7, 3, 4, 5, 6, 7));
+        System.out.println("\nInitialize binary tree");
+        PrintUtil.printTree(root);
+
+        // Pre-order traversal
+        path = new ArrayList<>();
+        res = new ArrayList<>();
+        preOrder(root);
+
+        System.out.println("\nOutput all root-to-node 7 paths");
+        for (List<TreeNode> path : res) {
+            List<Integer> vals = new ArrayList<>();
+            for (TreeNode node : path) {
+                vals.add(node.val);
+            }
+            System.out.println(vals);
+        }
+    }
+}
--- a/en/codes/java/chapter_backtracking/preorder_traversal_iii_compact.java
+++ b/en/codes/java/chapter_backtracking/preorder_traversal_iii_compact.java
@@ -0,0 +1,53 @@
+/**
+ * File: preorder_traversal_iii_compact.java
+ * Created Time: 2023-04-16
+ * Author: krahets (krahets@163.com)
+ */
+
+package chapter_backtracking;
+
+import utils.*;
+import java.util.*;
+
+public class preorder_traversal_iii_compact {
+    static List<TreeNode> path;
+    static List<List<TreeNode>> res;
+
+    /* Pre-order traversal: Example three */
+    static void preOrder(TreeNode root) {
+        // Pruning
+        if (root == null || root.val == 3) {
+            return;
+        }
+        // Attempt
+        path.add(root);
+        if (root.val == 7) {
+            // Record solution
+            res.add(new ArrayList<>(path));
+        }
+        preOrder(root.left);
+        preOrder(root.right);
+        // Retract
+        path.remove(path.size() - 1);
+    }
+
+    public static void main(String[] args) {
+        TreeNode root = TreeNode.listToTree(Arrays.asList(1, 7, 3, 4, 5, 6, 7));
+        System.out.println("\nInitialize binary tree");
+        PrintUtil.printTree(root);
+
+        // Pre-order traversal
+        path = new ArrayList<>();
+        res = new ArrayList<>();
+        preOrder(root);
+
+        System.out.println("\nOutput all root-to-node 7 paths, not including nodes with value 3");
+        for (List<TreeNode> path : res) {
+            List<Integer> vals = new ArrayList<>();
+            for (TreeNode node : path) {
+                vals.add(node.val);
+            }
+            System.out.println(vals);
+        }
+    }
+}
--- a/en/codes/java/chapter_backtracking/preorder_traversal_iii_template.java
+++ b/en/codes/java/chapter_backtracking/preorder_traversal_iii_template.java
@@ -0,0 +1,77 @@
+/**
+ * File: preorder_traversal_iii_template.java
+ * Created Time: 2023-04-16
+ * Author: krahets (krahets@163.com)
+ */
+
+package chapter_backtracking;
+
+import utils.*;
+import java.util.*;
+
+public class preorder_traversal_iii_template {
+    /* Determine if the current state is a solution */
+    static boolean isSolution(List<TreeNode> state) {
+        return !state.isEmpty() && state.get(state.size() - 1).val == 7;
+    }
+
+    /* Record solution */
+    static void recordSolution(List<TreeNode> state, List<List<TreeNode>> res) {
+        res.add(new ArrayList<>(state));
+    }
+
+    /* Determine if the choice is legal under the current state */
+    static boolean isValid(List<TreeNode> state, TreeNode choice) {
+        return choice != null && choice.val != 3;
+    }
+
+    /* Update state */
+    static void makeChoice(List<TreeNode> state, TreeNode choice) {
+        state.add(choice);
+    }
+
+    /* Restore state */
+    static void undoChoice(List<TreeNode> state, TreeNode choice) {
+        state.remove(state.size() - 1);
+    }
+
+    /* Backtracking algorithm: Example three */
+    static void backtrack(List<TreeNode> state, List<TreeNode> choices, List<List<TreeNode>> res) {
+        // Check if it's a solution
+        if (isSolution(state)) {
+            // Record solution
+            recordSolution(state, res);
+        }
+        // Traverse all choices
+        for (TreeNode choice : choices) {
+            // Pruning: check if the choice is legal
+            if (isValid(state, choice)) {
+                // Attempt: make a choice, update the state
+                makeChoice(state, choice);
+                // Proceed to the next round of selection
+                backtrack(state, Arrays.asList(choice.left, choice.right), res);
+                // Retract: undo the choice, restore to the previous state
+                undoChoice(state, choice);
+            }
+        }
+    }
+
+    public static void main(String[] args) {
+        TreeNode root = TreeNode.listToTree(Arrays.asList(1, 7, 3, 4, 5, 6, 7));
+        System.out.println("\nInitialize binary tree");
+        PrintUtil.printTree(root);
+
+        // Backtracking algorithm
+        List<List<TreeNode>> res = new ArrayList<>();
+        backtrack(new ArrayList<>(), Arrays.asList(root), res);
+
+        System.out.println("\nOutput all root-to-node 7 paths, requiring paths not to include nodes with value 3");
+        for (List<TreeNode> path : res) {
+            List<Integer> vals = new ArrayList<>();
+            for (TreeNode node : path) {
+                vals.add(node.val);
+            }
+            System.out.println(vals);
+        }
+    }
+}
--- a/en/codes/java/chapter_backtracking/subset_sum_i.java
+++ b/en/codes/java/chapter_backtracking/subset_sum_i.java
@@ -0,0 +1,55 @@
+/**
+ * File: subset_sum_i.java
+ * Created Time: 2023-06-21
+ * Author: krahets (krahets@163.com)
+ */
+
+package chapter_backtracking;
+
+import java.util.*;
+
+public class subset_sum_i {
+    /* Backtracking algorithm: Subset Sum I */
+    static void backtrack(List<Integer> state, int target, int[] choices, int start, List<List<Integer>> res) {
+        // When the subset sum equals target, record the solution
+        if (target == 0) {
+            res.add(new ArrayList<>(state));
+            return;
+        }
+        // Traverse all choices
+        // Pruning two: start traversing from start to avoid generating duplicate subsets
+        for (int i = start; i < choices.length; i++) {
+            // Pruning one: if the subset sum exceeds target, end the loop immediately
+            // This is because the array is sorted, and later elements are larger, so the subset sum will definitely exceed target
+            if (target - choices[i] < 0) {
+                break;
+            }
+            // Attempt: make a choice, update target, start
+            state.add(choices[i]);
+            // Proceed to the next round of selection
+            backtrack(state, target - choices[i], choices, i, res);
+            // Retract: undo the choice, restore to the previous state
+            state.remove(state.size() - 1);
+        }
+    }
+
+    /* Solve Subset Sum I */
+    static List<List<Integer>> subsetSumI(int[] nums, int target) {
+        List<Integer> state = new ArrayList<>(); // State (subset)
+        Arrays.sort(nums); // Sort nums
+        int start = 0; // Start point for traversal
+        List<List<Integer>> res = new ArrayList<>(); // Result list (subset list)
+        backtrack(state, target, nums, start, res);
+        return res;
+    }
+
+    public static void main(String[] args) {
+        int[] nums = { 3, 4, 5 };
+        int target = 9;
+
+        List<List<Integer>> res = subsetSumI(nums, target);
+
+        System.out.println("Input array nums = " + Arrays.toString(nums) + ", target = " + target);
+        System.out.println("All subsets summing to " + target + " res = " + res);
+    }
+}
--- a/en/codes/java/chapter_backtracking/subset_sum_i_naive.java
+++ b/en/codes/java/chapter_backtracking/subset_sum_i_naive.java
@@ -0,0 +1,53 @@
+/**
+ * File: subset_sum_i_naive.java
+ * Created Time: 2023-06-21
+ * Author: krahets (krahets@163.com)
+ */
+
+package chapter_backtracking;
+
+import java.util.*;
+
+public class subset_sum_i_naive {
+    /* Backtracking algorithm: Subset Sum I */
+    static void backtrack(List<Integer> state, int target, int total, int[] choices, List<List<Integer>> res) {
+        // When the subset sum equals target, record the solution
+        if (total == target) {
+            res.add(new ArrayList<>(state));
+            return;
+        }
+        // Traverse all choices
+        for (int i = 0; i < choices.length; i++) {
+            // Pruning: if the subset sum exceeds target, skip that choice
+            if (total + choices[i] > target) {
+                continue;
+            }
+            // Attempt: make a choice, update elements and total
+            state.add(choices[i]);
+            // Proceed to the next round of selection
+            backtrack(state, target, total + choices[i], choices, res);
+            // Retract: undo the choice, restore to the previous state
+            state.remove(state.size() - 1);
+        }
+    }
+
+    /* Solve Subset Sum I (including duplicate subsets) */
+    static List<List<Integer>> subsetSumINaive(int[] nums, int target) {
+        List<Integer> state = new ArrayList<>(); // State (subset)
+        int total = 0; // Subset sum
+        List<List<Integer>> res = new ArrayList<>(); // Result list (subset list)
+        backtrack(state, target, total, nums, res);
+        return res;
+    }
+
+    public static void main(String[] args) {
+        int[] nums = { 3, 4, 5 };
+        int target = 9;
+
+        List<List<Integer>> res = subsetSumINaive(nums, target);
+
+        System.out.println("Input array nums = " + Arrays.toString(nums) + ", target = " + target);
+        System.out.println("All subsets summing to " + target + " res = " + res);
+        System.out.println("Please note that the result of this method includes duplicate sets");
+    }
+}
--- a/en/codes/java/chapter_backtracking/subset_sum_ii.java
+++ b/en/codes/java/chapter_backtracking/subset_sum_ii.java
@@ -0,0 +1,60 @@
+/**
+ * File: subset_sum_ii.java
+ * Created Time: 2023-06-21
+ * Author: krahets (krahets@163.com)
+ */
+
+package chapter_backtracking;
+
+import java.util.*;
+
+public class subset_sum_ii {
+    /* Backtracking algorithm: Subset Sum II */
+    static void backtrack(List<Integer> state, int target, int[] choices, int start, List<List<Integer>> res) {
+        // When the subset sum equals target, record the solution
+        if (target == 0) {
+            res.add(new ArrayList<>(state));
+            return;
+        }
+        // Traverse all choices
+        // Pruning two: start traversing from start to avoid generating duplicate subsets
+        // Pruning three: start traversing from start to avoid repeatedly selecting the same element
+        for (int i = start; i < choices.length; i++) {
+            // Pruning one: if the subset sum exceeds target, end the loop immediately
+            // This is because the array is sorted, and later elements are larger, so the subset sum will definitely exceed target
+            if (target - choices[i] < 0) {
+                break;
+            }
+            // Pruning four: if the element equals the left element, it indicates that the search branch is repeated, skip it
+            if (i > start && choices[i] == choices[i - 1]) {
+                continue;
+            }
+            // Attempt: make a choice, update target, start
+            state.add(choices[i]);
+            // Proceed to the next round of selection
+            backtrack(state, target - choices[i], choices, i + 1, res);
+            // Retract: undo the choice, restore to the previous state
+            state.remove(state.size() - 1);
+        }
+    }
+
+    /* Solve Subset Sum II */
+    static List<List<Integer>> subsetSumII(int[] nums, int target) {
+        List<Integer> state = new ArrayList<>(); // State (subset)
+        Arrays.sort(nums); // Sort nums
+        int start = 0; // Start point for traversal
+        List<List<Integer>> res = new ArrayList<>(); // Result list (subset list)
+        backtrack(state, target, nums, start, res);
+        return res;
+    }
+
+    public static void main(String[] args) {
+        int[] nums = { 4, 4, 5 };
+        int target = 9;
+
+        List<List<Integer>> res = subsetSumII(nums, target);
+
+        System.out.println("Input array nums = " + Arrays.toString(nums) + ", target = " + target);
+        System.out.println("All subsets summing to " + target + " res = " + res);
+    }
+}