Day25(10.15)

216 组合总和 III

class Solution:
    def combinationSum3(self, k: int, n: int) -> List[List[int]]:
        rets=[]
        temp=[]
        def sub(temp,inp,cout,sums):
            if sums==n and cout==k:
                rets.append(temp[:])
                return
            if sums>n or cout>k:
                return
            for i in range(inp+1,10):
                temp.append(i)
                sub(temp,i,cout+1,sums+i)
                temp.pop()
        for i in range(1,10):
            sub([i],i,1,i)
        return rets

17

class Solution:
    def letterCombinations(self, digits: str) -> List[str]:
        if not digits:
            return []
        phoneMap = {
            "2": "abc",
            "3": "def",
            "4": "ghi",
            "5": "jkl",
            "6": "mno",
            "7": "pqrs",
            "8": "tuv",
            "9": "wxyz"
        }
        def sub(index):
            if index==len(digits):
                rets.append(''.join(ret))
            else:
                i=digits[index]
                for l in phoneMap[i]:
                    ret.append(l)
                    sub(index+1)
                    ret.pop()
        ret=[]
        rets=[]
        sub(0)
        return rets