小黑代码

class Solution:
    def checkInclusion(self, s1: str, s2: str) -> bool:
        # s1与s2的长度
        n_s1 = len(s1)
        n_s2 = len(s2)
        # 非法情况
        if n_s1 > n_s2:
            return False
        # 初始化差值向量
        count = [0] * 26
        # 判断初始状态是否成立
        for i in range(n_s1):
            count[ord(s1[i])-97] -= 1
            count[ord(s2[i])-97] += 1
        # 初始化差值
        diff = [i != 0 for i in count].count(True)
        # 初始窗口符合条件
        if not diff:
            return True
        # 开始进行滑动窗口
        for i in range(n_s2-n_s1):
            # 将要滑出的字符是否影响diff
            if count[ord(s2[i])-97] == 1:
                diff -= 1
            elif not count[ord(s2[i])-97]:
                diff += 1
            count[ord(s2[i])-97] -= 1
            # 将要滑入的字符是否影响diff
            if count[ord(s2[i+n_s1])-97] == -1:
                diff -= 1
            elif not count[ord(s2[i+n_s1])-97]:
                diff += 1
            count[ord(s2[i+n_s1])-97] += 1
            if not diff:
                return True
        return False

双指针法

class Solution:
    def checkInclusion(self, s1: str, s2: str) -> bool:
        # s1与s2长度
        n_s1 = len(s1)
        n_s2 = len(s2)
        if n_s1 > n_s2:
            return False
        # 计算s1的每个字符个数
        count = [0] * 26
        for i in range(n_s1):
            count[ord(s1[i])-97] += 1
        # 定义双指针
        left = 0
        right = 0
        while right < n_s2:
            # 计数该字符
            count[ord(s2[right])-97] -= 1
            # 不断移动做指针，使得该字符的偏差大于等于0
            while count[ord(s2[right])-97] < 0:
                count[ord(s2[left])-97] += 1
                left += 1
            right += 1
            if right - left == n_s1:
                return True
        return False

小黑生活

晚餐麻辣烫烤肠

王者峡谷，打得人家抬不起头

晚饭后和阿黄温榆河骑小黄车

以后可以继续学钢琴啦

晚上和阿黄老黑们小搞一下，中老黑遭遇情感危机

眼睛逐步恢复

早上没起来，直接午饭

给远在西安的大老黑寄党组织关系

回去打卡小汤3第5课

跟小老黑吃个老马拉面

准备零点出发跟中老黑阿黄小黄车骑行天津～