Java – a method to speed up full count sorting

I had a problem at hackerrank

Due to timeout, my first attempt passed all test cases except the last one After failing to propose a more efficient algorithm, I improved the code by using string builder instead of directly connecting strings This results in running times ranging from 5 seconds to 3.5 seconds

My question is, is there any other way to improve runtime? thank you.

Here is my code

public class Solution {

    public static void main(String[] args) {
        Scanner scanner = new Scanner(system.in);

        int N = scanner.nextInt();
        scanner.nextLine();

        int[] oriNum = new int[N];        
        String[] oriStr = new String[N];
        int[] count = new int[100];
        int[] indices = new int[100];
        int[] output = new int[N];

        // save the originals and the count array
        for (int i = 0; i < N; i++) {
            oriNum[i] = scanner.nextInt();
            oriStr[i] = scanner.nextLine().trim();
            count[oriNum[i]]++;
        }

        // accumulate the count array
        indices[0] = 0;
        for (int i = 1; i < 100; i++) {
            indices[i] = indices[i-1] + count[i-1];
        }

        // output order
        for (int i = 0; i < N; i++) {
            int num = oriNum[i];
            output[indices[num]++] = i;
        }

        int bar = N/2;
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < N; i++) {            
            int index = output[i];
            if (index < bar) 
                sb.append("- ");
            else 
                sb.append(oriStr[index]+ " ");
        }
        System.out.println(sb.toString());
    }
}

Solution

You should try using a normal buffer reader instead of a scanner The speed of the scanner is very slow. I participated in the programming competition, in which scanner is the only reason for "exceeding the time limit"