[Python手撕]小于n的最大数字

nums = [1,2,4,9]
target = 2533
nums.sort(reverse=True)
print(nums)
n = len(nums)

def dfs(index,num,length):
    print(index,num)
    if index == length-1:
        if num<=target:
            return num
        else:
            return None
    else:
        num *= 10
        for n in nums:
            res = dfs(index+1,num+n,length)
            if res:
                return res


print(dfs(-1,0,n))