Longest substring without repeating characters

       
        
        Given a string S, find the length of the longest substring without repeating characters.

        Example 1:

        Input:
        S = "geeksforgeeks"
        Output:
        7
        Explanation:
        Longest substring is "eksforg".

        
        

        Code
        
#include<bits/stdc++.h> 
using namespace std;
int main()
 {
    int i,j,k,n;
    string s;
    cin>>s;
    n=s.size();
    unordered_map<int,int>m;
    int mx=INT_MIN;
    i=0,j=0;
    while(j<n)
    {
        m[s[j]]++;
        if(m.size()==j-i+1)
        {
            mx=max(mx,j-i+1);
            j++;
        }
        else if(m.size()<j-i+1)
        {
            while(m.size()<j-i+1)
            {
                m[s[i]]--;
    
                if(m[s[i]]==0)
                 m.erase(s[i]);
                 i++;
            }
            j++;
        }
    }
    cout<<mx<<endl;
	    
	 
	return 0;
}