python实现输出八皇后的第n个解

你可以使用回溯算法来解决八皇后问题。下面是一个示例的 Python 代码，用于输出八皇后问题的第 n 个解：

def solve_n_queens(n, row=0, positions=[], solutions=[]):
    if row == n:
        solutions.append(positions[:])
        return

    for col in range(n):
        if is_valid(row, col, positions):
            positions.append(col)
            solve_n_queens(n, row + 1, positions, solutions)
            positions.pop()

def is_valid(row, col, positions):
    for i in range(row):
        if positions[i] == col or \
           positions[i] - i == col - row or \
           positions[i] + i == col + row:
            return False
    return True

def print_solution(n, solution):
    for row in range(n):
        line = ""
        for col in range(n):
            if solution[row] == col:
                line += "Q "
            else:
                line += ". "
        print(line)
    print()

n = 8  # 八皇后问题的棋盘大小
k = 5  # 要输出的第 k 个解

solutions = []
solve_n_queens(n, solutions=solutions)

if k <= len(solutions):
    print(f"The {k}th solution of {n}-queens problem:")
    print_solution(n, solutions[k - 1])
else:
    print(f"There are only {len(solutions)} solutions for {n}-queens problem.")

你可以将 `n` 设置为 8，`k` 设置为你想要输出的解的编号。请注意，该代码会输出所有的解，所以如果你想要输出的解超出了实际解的数量，它会给出一个相应的提示。