Python回溯法(Backtracking)的具体使用

def solve_n_queens(n):
    def is_safe(board, row, col):
        # 检查同一列是否有皇后
        for i in range(row):
            if board[i] == col or \
               board[i] - i == col - row or \
               board[i] + i == col + row:
                return False
        return True

    def backtrack(row):
        if row == n:
            solutions.append(board[:])
            return
        for col in range(n):
            if is_safe(board, row, col):
                board[row] = col
                backtrack(row + 1)

    solutions = []
    board = [-1] * n
    backtrack(0)
    return solutions

# 示例
n_queens_solutions = solve_n_queens(8)
for solution in n_queens_solutions:
    print(solution)

def generate_subsets(nums):
    def backtrack(start, path):
        subsets.append(path[:])
        for i in range(start, len(nums)):
            path.append(nums[i])
            backtrack(i + 1, path)
            path.pop()

    subsets = []
    backtrack(0, [])
    return subsets

# 示例
nums = [1, 2, 3]
subsets = generate_subsets(nums)
for subset in subsets:
    print(subset)