Java 代码

import java.util.LinkedList;
import java.util.Scanner;
public class Main {
    public static void main(String[] args){
        Scanner input = new Scanner(System.in);
        String num = input.nextLine();
        int k = input.nextInt();
        if(k == num.length()){
            System.out.println(0);return;
        }
        LinkedList<Integer> stack = new LinkedList<>();
        int cnt = 0;
        for(int i = 0 ; i < num.length() ; i++){
            while(!stack.isEmpty() && cnt < k && stack.peek() > (num.charAt(i) - '0')){
                cnt++;
                stack.pop();
            }
            stack.push(num.charAt(i) - '0');
        }
        while(cnt < k){
            stack.pop();cnt++;
        }
        StringBuilder sb = new StringBuilder();
        while(!stack.isEmpty()){
            sb.append(stack.pop());
        }
        String res = sb.reverse().toString();
        int i = 0;
        for(; i < res.length() ; i++){
            if(res.charAt(i) != '0')break;
        }
        System.out.println(res.substring(Math.min(i,res.length() - 1)));
    }
}