text: 
  #include <string.h>
  #include <iostream>
  #include "ispermutation.h"
  
  bool isPermutation(const char* lhs, const char* rhs) {
      
      if(!lhs || !rhs) { 
          return false;
      }
  
      int counts[255] = { 0 };
  
      const int lhsLength = strlen(lhs);
      const int rhsLength = strlen(rhs);
  
      if(lhsLength != rhsLength) {
          return false;
      }
  
      for(int i = 0; i < lhsLength; ++i) {
          counts[lhs[i]]++;
          counts[rhs[i]]--;
      }
  
      for(int i = 0; i < 255; ++i) {
          if(counts[i] != 0) {
              return false;
          }
      }
  
      return true;
  }
  
  