make-large-number.java

import java.util.*;
class Solution {
    public String solution(String number, int k) {
		char[] arr = number.toCharArray();
		Stack<Integer> list = new Stack<>();
		
		for (int i = 0; i < arr.length; i++) {
			int curr = (int) arr[i] - '0';
			while (!list.isEmpty() && k>0 && list.peek() < curr) {
				list.pop();
				k -= 1;
			}
			
			list.push(curr);
		}
        
        while (k > 0) {
        	list.pop();
			k-=1;
        }
        
        StringBuilder sb = new StringBuilder();
        for(int i : list) sb.append(i);
        
        return sb.toString();
    }
}