import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner console = new Scanner(System.in);
        int price = console.nextInt();
        int cost = 0;

        //write your code here......
        double x =1.0;
        if(price>=5000){
           x = 0.6;
        }
        else if (price>=2000){
            x = 0.7;
        }
        else if(price>=500){
            x = 0.8;
        }
        else if(price>=100){
            x = 0.9;
        }
        cost = (int)(x*price);



        System.out.println(cost);
    }
}

正常枚举就好了,and发现了更好的解法

//考虑到购买5000元东西的人很少,应从小到大判断,以减少判断次数

cost=(int)(price<100? price : price<500

? price*0.9: price<2000

? price*0.8: price<5000

? price*0.7: price*0.6);

一个是三目运算符,另外应该是这个最简运算思路