力扣每日一题1023

10.23

#字符串匹配
class Solution(object):
    def countSeniors(self, details):
        """
        :type details: List[str]
        :rtype: int
        """
        ans = 0
        for person in details:
            if int(person[11:13]) > 60:
                ans+=1
        return ans

10.24（程序员节）

#动态规划
class Solution(object):
    def numRollsToTarget(self, n, k, target):
        """
        :type n: int
        :type k: int
        :type target: int
        :rtype: int
        """
        # mod = 10**9 + 7
        # f = [[0] * (target + 1) for _ in range(n + 1)]
        # f[0][0] = 1
        # for i in range(1, n + 1):
        #     for j in range(i,target + 1):
        #         for x in range(1, k + 1):
        #             if j - x >= 0:
        #                 f[i][j] = (f[i][j] + f[i - 1][j - x]) % mod
        # return f[n][target]
        mod = 10**9 + 7
        f = [1] + [0] * target
        #挨个拿n个骰子
        for i in range(1, n + 1):
            g = [0] * (target + 1)
            for j in range(i,target + 1):
                for x in range(1, k + 1):
                    if j - x >= 0:
                        g[j] = (g[j] + f[j - x]) % mod
            f = g
        return f[target]

10.25

#回溯  难
class Solution(object):
    def punishmentNumber(self, n):
        """
        :type n: int
        :rtype: int
        """
        def dfs(s, pos, tot, target):
            if pos == len(s):
                return tot == target
            sum = 0
            for i in range(pos, len(s)):
                sum = sum * 10 + int(s[i])
                if sum + tot > target:
                    break
                if dfs(s, i + 1, sum + tot, target):
                    return True
            return False
        res = 0
        for i in range(1, n + 1):
            if dfs(str(i * i), 0, 0, i):
                res += i * i
        return res

 10.26

from collections import Counter
class Solution(object):
    def countDigits(self, num):
        """
        :type num: int
        :rtype: int
        """
        ans = 0
        tmp = dict(Counter(str(num)))
        for k,v in tmp.items():
            if num % int(k) == 0:
                ans += v
 
        return ans