Next Greater Element To The Right

I/P: {1, 3, 4, 7, 2, 6, 8} 

O/P: {3, 4, 7, 8, 6, 8, -1} 

package pep.Day25;

import java.lang.reflect.Array;
import java.util.Arrays;
import java.util.Stack;

public class Next_Greater_Element_To_The_RIght {
    public static void main(String[] args) {
        int[] arr = new int[]{1, 3, 4, 7, 2, 6, 8};

        int[] ans = solve(arr);
        display(ans);
    }

    private static void display(int[] ans) {
        for (int i : ans)
            System.out.print(i + "\t");

        System.out.println();
    }

    private static int[] solve(int[] arr) {
        int n = arr.length;
        Stack<Integer> stack = new Stack<>();
        int[] ans = new int[n];

        for (int i = n - 1; i >= 0; i--) {
            while (!stack.isEmpty() && stack.peek() <= arr[i])
                stack.pop();
            ans[i] = stack.isEmpty() ? -1 : stack.peek();
            stack.push(arr[i]);
        }
        return ans;
    }

}

Time Complexity: O(n)

Space Complexity: O(n)