Matter++

input/code.cpp: In function 'void solve()':
input/code.cpp:31:23: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   31 |     for (int i = 0; i < amounts.size(); i++)
      |                     ~~^~~~~~~~~~~~~~~~
input/code.cpp:39:14: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   39 |     while (r <= text.size())
      |            ~~^~~~~~~~~~~~~~
input/code.cpp:42:27: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   42 |         for (int i = 0; i < amounts.size(); i++)
      |                         ~~^~~~~~~~~~~~~~~~
input/code.cpp:48:19: warning: comparison of integer expressions of different signedness:...

#include <iostream>
#include <vector>
#include <array>
#include <string>
#include <algorithm>
#include <numeric>
#include <unordered_map>
#include <unordered_set>
#include <set>
#include <queue>
#include <climits>
#include <cmath>
#include <functional>
#include <type_traits>
#include <bitset>
#include <fstream>
 
#define int long long
using namespace std;


void solve() {
    int w;
    string text;
    cin >> w >> text;

    int l = 0;
    int r = 0;

    vector<int> amounts(26);
    for (int i = 0; i < amounts.size(); i++)
    {
        amounts[i] = 0;
    }

    int minVal = LLONG_MAX/2;
    int minIdx = -1;

    while (r <= text.size())
    {
        int val = 0;
        for (int i = 0; i < amounts.size(); i++)
        {
            val += amounts[i] * amounts[i];
        }
        if (val < w)
        {
            if (r == text.size())
                break;
            amounts[text[r]-'a']++;
            r++;
            continue;
        }
        if (r-l < minVal)
        {
            minVal = r-l;
            minIdx = l;
        }
        amounts[text[l]-'a']--;
        l++;
    }

/*
    int val = 0;
    for (int i = 0; i < amounts.size(); i++)
    {
        val += amounts[i] * amounts[i];
    }
    if (val >= w)
    {
        minIdx = l;
        minVal = r-l;
    }
    */

    //cout << minVal << " " << minIdx << endl;
    /*
    if (minIdx == -1)
    {
        minIdx = 0;
        minVal = text.size();
    }
    */
    //else
        cout << text.substr(minIdx, minVal);
    
}
 
signed main() {
    //cin.tie(0);
    //ios_base::sync_with_stdio(false);
    int t = 1;
    //ifstream f("testcase.txt");
    //cin.rdbuf(f.rdbuf());
    //cin >> t;
    while (t--) { solve(); }
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED

Test 13

Verdict: ACCEPTED

Test 14

Verdict: ACCEPTED

Test 15

Verdict: ACCEPTED

Test 16

Verdict: ACCEPTED

Test 17

Verdict: ACCEPTED

Test 18

Verdict: ACCEPTED

Test 19

Verdict: ACCEPTED

Test 20

Verdict: ACCEPTED

Test 21

Verdict: ACCEPTED

Test 22

Verdict: ACCEPTED

Test 23

Verdict: ACCEPTED

Test 24

Verdict: ACCEPTED

Test 25

Verdict: ACCEPTED

Test 26

Verdict: ACCEPTED

Test 27

Verdict: ACCEPTED

Test 28

Verdict: ACCEPTED

Test 29

Verdict: ACCEPTED

Test 30

Verdict: ACCEPTED

Test 31

Verdict: ACCEPTED

Test 32

Verdict: ACCEPTED

Test 33

Verdict: ACCEPTED

Test 34

Verdict: ACCEPTED

Test 35

Verdict: ACCEPTED

Test 36

Verdict: ACCEPTED

Test 37

Verdict: ACCEPTED

Test 38

Verdict: ACCEPTED

Test 39

Verdict: ACCEPTED

Test 40

Verdict: ACCEPTED

Test 41

Verdict: ACCEPTED

Test 42

Verdict: ACCEPTED

Test 43

Verdict: ACCEPTED

Test 44

Verdict: ACCEPTED

Test 45

Verdict: ACCEPTED

Test 46

Verdict: ACCEPTED

Test 47

Verdict: ACCEPTED

Test 48

Verdict: ACCEPTED

Test 49

Verdict: ACCEPTED

Test 50

Verdict: ACCEPTED

Test 51

Verdict: ACCEPTED

Test 52

Verdict: ACCEPTED

Test 53

Verdict: ACCEPTED

Test 54

Verdict: ACCEPTED

Test 55

Verdict: ACCEPTED

Test 56

Verdict: ACCEPTED

Test 57

Verdict: ACCEPTED

Test 58

Verdict: ACCEPTED

Test 59

Verdict: ACCEPTED

Test 60

Verdict: ACCEPTED

Test 61

Verdict: ACCEPTED

Test 62

Verdict: ACCEPTED

Test 63

Verdict: ACCEPTED

Test 64

Verdict: ACCEPTED

Test 65

Verdict: ACCEPTED

Test 66

Verdict: ACCEPTED

Test 67

Verdict: ACCEPTED

Test 68

Verdict: ACCEPTED

Test 69

Verdict: ACCEPTED

Test 70

Verdict: ACCEPTED

Test 71

Verdict: ACCEPTED