ALGO-1005 数字游戏 蓝桥杯

# 此题要用到深度遍历dfs
# 全排列问题

def dfs(depth, n, sumR, arr, visted, flag):
    nums = []
    if flag[0]:        
        return
    if depth > n:
        # 此处复制数组要注意，不可直接赋值给nums
        for i in arr:
            nums.append(i)
        if numberGame(n, nums, sumR):
            flag[0] = 1
            for i in range(1, n+1):
                print(arr[i],"", end="")
        return
    else:
        for i in range(1, n+1):
            if not visted[i]:
                arr[depth] = i
                visted[i] = True
                dfs(depth+1, n, sumR, arr, visted, flag)
                visted[i] = False
    
# 判断数组是否符合条件
def numberGame(n, nums, sumR):
    temp = n
    while temp > 0:
        for i in range(1, temp):
            nums[i] = nums[i]+nums[i+1]
        temp -= 1

    return nums[1] == sumR

inp = input().split()
n = int(inp[0])
sumR = int(inp[1])
# 前后各扩宽一格，方便我们对数组判断时不用考虑边界问题
visted = [False] * (n+2)
arr = [0] * (n+2)
flag = [0]
dfs(1, n, sumR, arr, visted, flag)