n选m

思路

从1遍历到n，对于一个数字要么选要么不选，拿到m个数时停止

def dfs(i, n, m, res):
    if len(res) == m:
        print(" ".join(map(str, res)))
    else:
        if i <= n:
            res.append(i)
            dfs(i+1, n, m, res)
            res.pop()
            dfs(i+1, n, m, res)


def func():
    while True:
        try:
            n, m = map(int, input().strip().split())
            while n is not None:
                dfs(1, n, m, [])
                n, m = map(int, input().strip().split())
        except EOFError:
            break
        finally:
            break
    
if __name__ == "__main__":
    func()