Help me in solving SUMMODE problem

help
,
1

My issue

what’s the problem with this code bro? @dpcoder_007

My code

import java.util.*;
import java.lang.*;
import java.io.*;
class Codechef {
    public static void main(String[] args) throws java.lang.Exception {
        Scanner scn = new Scanner(System.in);
        int t = scn.nextInt();
        while (t-- > 0) {
            int n = scn.nextInt();
            scn.nextLine(); // Consume newline character
            String st = scn.nextLine();
            long ans = ((long) n * (n + 1)) / 2;
            int count = 0;
            for (int i = 0; i < n; i++) {
                for (int j = i; j < n; j++) {
                    HashMap<Character, Integer> hm = new HashMap<>();
                    String st1 = st.substring(i, j + 1);
                    for (int k = 0; k < st1.length(); k++) {
                        char c = st1.charAt(k);
                        hm.put(c, hm.getOrDefault(c, 0) + 1);
                    }
                    if (hm.getOrDefault('1', 0) == hm.getOrDefault('0', 0)) {
                        count++;
                    }
                }
            }
            System.out.println(ans + count);
        }
        scn.close();
    }
}

Problem Link: Sum of Modes Practice Coding Problem

2

@karthi04041
brute force logic will give u tle .
U have to optimize your solution to O(n) time complexity .