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| class Solution {
public:
bool checkInclusion(string s1, string s2) {
const int n1 = s1.size(), n2 = s2.size();
if (n1 > n2) return false;
vector<int> freq(26), winFreq(26);
int cnt = 0, winCnt = 0;
for (char c : s1)
if (freq[c - 'a']++ == 0)
++cnt;
int left = 0, right = 0;
while (right < n2) {
int idx = s2[right++] - 'a';
if (freq[idx] > 0)
if (++winFreq[idx] == freq[idx])
++winCnt;
while (winCnt == cnt) {
if (right - left == n1) return true;
idx = s2[left++] - 'a';
if (freq[idx] > 0)
if (--winFreq[idx] < freq[idx])
--winCnt;
}
}
return false;
}
};
|