Add the initial EN translation for C++ code (#1346)

2026-04-08 13:21:19 +08:00 · 2024-05-06 13:31:46 +08:00
parent 9e4017b3fb
commit 8e60d12151
111 changed files with 6993 additions and 9 deletions
--- a/en/codes/cpp/chapter_backtracking/n_queens.cpp
+++ b/en/codes/cpp/chapter_backtracking/n_queens.cpp
@@ -0,0 +1,65 @@
+/**
+ * File: n_queens.cpp
+ * Created Time: 2023-05-04
+ * Author: krahets (krahets@163.com)
+ */
+
+#include "../utils/common.hpp"
+
+/* Backtracking algorithm: n queens */
+void backtrack(int row, int n, vector<vector<string>> &state, vector<vector<vector<string>>> &res, vector<bool> &cols,
+               vector<bool> &diags1, vector<bool> &diags2) {
+    // When all rows are placed, record the solution
+    if (row == n) {
+        res.push_back(state);
+        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[row][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[row][col] = "#";
+            cols[col] = diags1[diag1] = diags2[diag2] = false;
+        }
+    }
+}
+
+/* Solve n queens */
+vector<vector<vector<string>>> nQueens(int n) {
+    // Initialize an n*n size chessboard, where 'Q' represents the queen and '#' represents an empty spot
+    vector<vector<string>> state(n, vector<string>(n, "#"));
+    vector<bool> cols(n, false);           // Record columns with queens
+    vector<bool> diags1(2 * n - 1, false); // Record main diagonals with queens
+    vector<bool> diags2(2 * n - 1, false); // Record minor diagonals with queens
+    vector<vector<vector<string>>> res;
+
+    backtrack(0, n, state, res, cols, diags1, diags2);
+
+    return res;
+}
+
+/* Driver Code */
+int main() {
+    int n = 4;
+    vector<vector<vector<string>>> res = nQueens(n);
+
+    cout << "Input the dimensions of the chessboard as " << n << endl;
+    cout << "Total number of queen placement solutions = " << res.size() << endl;
+    for (const vector<vector<string>> &state : res) {
+        cout << "--------------------" << endl;
+        for (const vector<string> &row : state) {
+            printVector(row);
+        }
+    }
+
+    return 0;
+}