Non repeating.cpp

#include <bits/stdc++.h> 
using namespace std; 
#define NO_OF_CHARS 256 
  
int firstNonRepeating(char *str) 
{ 
    pair<int, int> arr[NO_OF_CHARS]; 
  
    for (int i = 0; str[i]; i++) 
    { 
        (arr[str[i]].first)++; 
        arr[str[i]].second = i; 
    } 
  
    int res = INT_MAX; 
    for (int i = 0; i < NO_OF_CHARS; i++) 
  
        if (arr[i].first == 1) 
            res = min(res, arr[i].second); 
  
    return res; 
} 
  
int main() 
{ 
    char str[] = "geeksforgeeks"; 
    int index = firstNonRepeating(str); 
    if (index == INT_MAX) 
        printf("Either all characters are "
              "repeating or string is empty"); 
    else
        printf("First non-repeating character"
               " is %c", str[index]); 
    return 0; 
}