UVA 417 - Word Index c++ implementation

Problem Type: map (Java TreeMap)
Problem Link: https://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&page=show_problem&category=24&problem=358&mosmsg=Submission+received+with+ID+20216008

Source code :

 /***
    Tarequzzaman Khan
    CSE'12
    2012331514
    */
#include<bits/stdc++.h>
using namespace std;
unordered_map<string,int>mp;
void load()
{
    queue<string> q;
    string s = "";
    int cou =1;
    for(int i=97; i<=122; i++)
    {
        char c = i;
        s+=c;
        mp[s]=cou;
        q.push(s);
        cou ++;
        s="";
    }
    while(!q.empty())
    {
        string s = q.front();
        q.pop();
        for(int i=97; i<=122; i++)
        {
            char c = i;
            int len = s.length();
            if(s[len-1]<c)
            {
                string m = s+c;
                if(m.length()>5)
                    break;
                mp[m]=cou;
                q.push(m);
                cou ++;
            }
        }
    }
}
int main()
{
 /***
    Tarequzzaman Khan
    CSE'12
    2012331514
    */
    load();
    string s ;
    while(cin >>s)
    {
     cout << mp[s] << endl;
    }
}