translation: Add Python and Java code for EN version (#1345)

* Add the intial translation of code of all the languages

* test

* revert

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* Add Python and Java code for EN version

en/codes/python/chapter_backtracking/n_queens.py

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+"""
+File: n_queens.py
+Created Time: 2023-04-26
+Author: krahets (krahets@163.com)
+"""
+
+
+def backtrack(
+    row: int,
+    n: int,
+    state: list[list[str]],
+    res: list[list[list[str]]],
+    cols: list[bool],
+    diags1: list[bool],
+    diags2: list[bool],
+):
+    """Backtracking algorithm: n queens"""
+    # When all rows are placed, record the solution
+    if row == n:
+        res.append([list(row) for row in state])
+        return
+    # Traverse all columns
+    for col in range(n):
+        # Calculate the main and minor diagonals corresponding to the cell
+        diag1 = row - col + n - 1
+        diag2 = row + col
+        # Pruning: do not allow queens on the column, main diagonal, or minor diagonal of the cell
+        if not cols[col] and not diags1[diag1] and not 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
+
+
+def n_queens(n: int) -> list[list[list[str]]]:
+    """Solve n queens"""
+    # Initialize an n*n size chessboard, where 'Q' represents the queen and '#' represents an empty spot
+    state = [["#" for _ in range(n)] for _ in range(n)]
+    cols = [False] * n  # Record columns with queens
+    diags1 = [False] * (2 * n - 1)  # Record main diagonals with queens
+    diags2 = [False] * (2 * n - 1)  # Record minor diagonals with queens
+    res = []
+    backtrack(0, n, state, res, cols, diags1, diags2)
+
+    return res
+
+
+"""Driver Code"""
+if __name__ == "__main__":
+    n = 4
+    res = n_queens(n)
+
+    print(f"Input chessboard dimensions as {n}")
+    print(f"The total number of queen placement solutions is {len(res)}")
+    for state in res:
+        print("--------------------")
+        for row in state:
+            print(row)