Java 中的数据结构

高性能输入输出#

BufferedReader in =new BufferedReader(new InputStreamReader(System.in));
PrintWriter out = new PrintWriter(System.out);

获取输入#

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        while (in.hasNextInt()) {
            int a = in.nextInt();
            int b = in.nextInt();
            System.out.println(a + b);
        }
    }
}

格式化输出#

// 保留两位小数
System.out.printf("%.2f%n", divisor*1.0/a);

Comparator#

Java 中的容器在排序时都要使用到比较器

Comparator<Integer> comparator = new Comparator<>() {
    @Override
    public int compare(Integer num1, Integer num2) {
        return num2 - num1;
    }
};