Write a program to find first repeating characters in string.

Given a string we have to find first repeating character in string and print the result.

Example:

input:aaabasbb
output:a

Logic:

Step 1- make a freq array.
step 2- count character of string
step 3-check in count array and check for first repeating character.

Code-

#include<bits/stdc++.h>
using namespace std;
int main()
{
    string s;
    cin>>s;
  int hash[26]={0};
    for(int i=0;i<s.length();i++)
    {
     hash[s[i]-'a']++;  
    }
 for(int i=0;i<s.length();i++)
 {
     if(hash[s[i]-'a']>1)
     {
         cout<<s[i]<<endl;
         break;
     }
 }
   
    
}

Output:

aababs
a

Time complexity:0(N)

Space Complexity:O(N)