567. Permutation in String

PermutationString.cs

public class Solution {
  public bool CheckInclusion(string s1, string s2) {
    if(s1.Length > s2.Length)
      return false;
    var s2Index = 0;
    var s1Freq = new int[26];
    foreach(var letter in s1)
      s1Freq[letter - 'a']++;
    
    while(s2Index < s2.Length){
      if(s1Freq[s2[s2Index] - 'a'] != 0){
        var j = 0;
        var s2Freq = new int[26];
        var found = true;
        while(j < s1.Length && j + s2Index < s2.Length){
          var curKey = s2[j + s2Index] - 'a';
          s2Freq[curKey]++;
          if(s2Freq[curKey] > s1Freq[curKey]){
            found = false;
            break;
          }
          j++;
        }
        if(found){
          var freqAreEq = true;
          for(var i = 0; i < s1Freq.Length; ++i){
            if(s1Freq[i] != s2Freq[i]){
              freqAreEq = false;
              break;
            }
          }
          if(freqAreEq)
            return true;
        }
      }
      s2Index++;
    }
    return false;
  }
}
/*
"ccaab"
"eid - abcca - ooo"  True

"ccaab"
"eid - <c[abcc>a] - ooo"  True

"ccaab"
"eid - abccca - ooo"  False

"cccaab"
"eid - abcca - ooo"  False

"ccb"
"eid - acc - ooo"  False

"eidbaooo"        False
"ab"



"ccaab"
"eidabccaooo"
"ccaab"
"eidcabccaooo"
"ccaab"
"eidabcccaooo"
"cccaab"
"eidabccaooo"
"ccb"
"eidaccooo"
"eidbaooo"
"ab"
"ab"
"eidbaooo"
"ab"
"eidboaoo"


*/