First non-repeating character using one traversal of string in C++

In this tutorial, we are going to learn how to find the first non-repeating character in the given string. Let's see an example.

Input −tutorialspoint

Output −u

Let's see the steps to solve the problem.

Initialize the string.
Initialize a map char and array to store the frequency of the characters in the string.
Iterate over the string.
Find the frequency of each character and store them in the map.
Store the index of the character as well.
Iterate over the character frequencies in the map.
Print the first character with the frequency 1.

Example

Let's see the code.

#include <bits/stdc++.h>
#include <map>
using namespace std;
void findDistinctCharacters(string random_string) {
   // initializing char count
   map<char, int[2]> chars;
   // iterating over the string
   for (int i = 0; i < random_string.size(); ++i){
      chars[random_string[i]][0]++;
      chars[random_string[i]][1] = i;
   }
   int char_index = INT_MAX;
   // printing the first char with frequency 1
   for (auto item: chars) {
      // checking the frequency
      if (item.second[0] == 1) {
         char_index = min(char_index, item.second[1]);
      }
   }
   // printing the first char with frequency 1
   cout << random_string[char_index] << u;
}
int main() {
   findDistinctCharacters("tutorialspoint");
   return 0;
}

Output

If you run the above code, then you will get the following result.

Conclusion

If you have any queries in the tutorial, mention them in the comment section.

Hafeezul Kareem

Published on 29-Dec-2020 11:09:29

Previous Page Print Page