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class Solution {
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  public boolean checkInclusion(String s1, String s2) {
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    if (s1.length() > s2.length()) {
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      return false;
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    }
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    int[] s1Count = new int[26];
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    int[] s2Count = new int[26];
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    for (int i = 0; i < s1.length(); i++) {
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      char c = s1.charAt(i);
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      char s = s2.charAt(i);
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      s1Count[c - 'a'] += 1;
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      s2Count[s - 'a'] += 1;
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    }
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    int matches = 0;
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    for (int i = 0; i < 26; i++) {
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      if (s1Count[i] == s2Count[i]) {
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        matches += 1;
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      }
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    }
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    int left = 0;
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    for (int right = s1.length(); right < s2.length(); right++) {
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      if (matches == 26) {
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        return true;
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      }
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      int index = s2.charAt(right) - 'a';
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      s2Count[index] += 1;
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      if (s1Count[index] == s2Count[index]) {
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        matches += 1;
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      } else if (s1Count[index] + 1 == s2Count[index]) {
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        matches -= 1;
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      }
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      index = s2.charAt(left) - 'a';
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      s2Count[index] -= 1;
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      if (s1Count[index] == s2Count[index]) {
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        matches += 1;
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      } else if (s1Count[index] - 1 == s2Count[index]) {
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        matches -= 1;
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      }
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      left += 1;
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    }
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    if (matches == 26) {
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      return true;
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    }
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    return false;
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  }
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}