Smallest window in a string containing all the characters of another string.

Smallest window in a string containing all the characters of another string.

Given a string S and text T. Output the smallest window in the string S having all characters of the text T. Both the string S and text T contains lowercase English alphabets.

Output the smallest window of the string containing all the characters of the text. If such a window doesn`t exist or this task can not be done then print -1.

Example:

Input:

3

timetopractice

toc

zoomlazapzo

oza

mpsbqedzsqyskjqydomdanqfmtqri

rrbqrnbbzyijnwfnimshbjimbfe

Output:

toprac

apzo

-1

#include <bits/stdc++.h>

using namespace std;

int main() {
    //code    
    int t;
    cin >> t;
    while (t--) {
        string s, s1;
        cin >> s >> s1;

        unordered_map < char, int > mp;
        for (int i = 0; i < s1.size(); ++i) {
            mp[s1[i]]++;
        }

        int n = s.size(), r = 0, i = 0, j = 0, l = 0;
        int miss = s1.size();

        while (r < n) {
            if (mp[s[r]] > 0) {

                miss -= 1;
            }
            mp[s[r]] -= 1;

            ++r;
            while (miss == 0) {
                if (j == 0 || r - l < j - i) {
                    i = l, j = r;
                }

                mp[s[l]] += 1;
                if (mp[s[l]] > 0) {
                    ++miss;

                }
                ++l;
            }

        }

        if (j - i != 0)
            cout << s.substr(i, j - i) << endl;
        else
            cout << -1 << endl;
    }
    return 0;
}