text: //question : https://leetcode.com/problems/valid-anagram/
  //runtime  : 0ms
  bool isAnagram(char* s, char* t) {
      if (strlen(s)!=strlen(t)) return false;
      int i,j,len=strlen(s),count1[25]={0},count2[25]={0};
      for (i=0;i<len;i++) {
          count1[s[i]-97]++;
          count2[t[i]-97]++;
      }
      for (i=0;i<26;i++)
          if (count1[i] != count2[i]) return false;
      return true;
  }