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Java输入输出

只有输出

Java

只有输出

public class Main{
    public static void main(String[] args){
        System.out.printlin("Hello World!");
    }
}

单组A+B

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

多组A + B

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

多组A + B（T组形式）

public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int t = sc.nextInt();
        for(int i = 0;i < t;i ++){
            int a = sc.nextInt();
        	int b = sc.nextInt();
            System.out.println(a + b);
        }
    }
}

多组A + B（0尾形式）

public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        while(true){
            int a = sc.nextInt();
        	int b = sc.nextInt();
            if(a == 0 && b == 0) break;
            System.out.println(a + b);
        }
    }
}

单组 （一维数组）

public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        long sum = 0;
        for(int i = 0;i < n;i ++){
            sum += sc.nextInt();
        }
        System.out.println(sum);
    }
}

多组 （一维数组，T组形式）

public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        while(sc.hasNext()){
            int t = sc.nextInt();
            long sum = 0;
            for(int i = 0;i < t;i ++){
                sum += sc.nextInt();
            }
            System.out.println(sum);
        }
    }
}

单组 （二维数组）

public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int m = sc.nextInt();
        long sum = 0;
        for(int i = 0;i < n;i ++){
            for(int j = 0;j < m;j ++){
                sum += sc.nextInt();
            }
        }
        System.out.println(sum);
    }
}

多组 （二维数组，T组形式）

public class Main{
    public class void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int t = sc.nextInt();
        for(int i = 0;i < t;i ++){
            int n = sc.nextInt();
            int m = sc.nextInt();
            long sum = 0;
            for(int j = 0;j < n;j ++){
                for(int k = 0;k < m;k ++){
                    sum += sc.nextInt();
                }
            }
            System.out.println(sum);
        }
    }
}

单组 （字符串）

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        sc.nextLine();
        String s = new StringBuilder(sc.nextLine()).reverse().toString();
        System.out.println(s);
    }
}

多组 （字符串 t组形式）

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int t = sc.nextInt();
        for(int i = 0;i < t;i ++){
            int n = sc.nextInt();
            sc.nextLine();
            String s = new StringBuilder(sc.nextLine()).reverse().toString();
            System.out.println(s);
        }
    }
}

单组 （二维字符数组）

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt(), m = sc.nextInt();
        sc.nextLine();
        String[] ss = new String[n];
        for(int i = 0;i < n;i ++){
            ss[i] = new StringBuilder(sc.nextLine()).reverse().toString();
        }
        for(int i = n - 1;i >= 0; -- i){
            System.out.println(ss[i]);
        }
    }
}

多组 （带空格的字符串 t组形式）

输入：

3 9 one space 11 two spaces 14 three spaces

输出：

ecapseno secapsowt secapseerht

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int t = sc.nextInt();
        sc.nextLine();
        for(int i = 0;i < t;i ++){
            sc.nextLine();
            String s = new StringBuilder(sc.nextLine().replace(" ", "")).reverse().toString();
            System.out.println(s);
        }
    }
}

单组 （保留小数位数）

**输入：**1.23

**输出：**1.230

**输入：**114.514

输出：114.514

**输入：**123

**输出：**123.000

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        double num = sc.nextDouble();
        System.out.printf("%.3f", num);
    }
}

单组 （补充前导零）

**输入：**123

**输出：**000000123

**输入：**123456789

**输出：**123456789

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int num = sc.nextInt();
        System.out.printf("%9d", num);
    }
}

单组 判断YES/NO

**输入：**123

**输出：**YES

**输入：**124

**输出：**NO

import java.util.Scanner;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        if (n % 2 != 0){
            System.out.println("YES");
        } else{
            System.out.println("NO");
        }
        
    }
}

单组 （spj判断浮点误差）

**输入：**123

**输出：**47529.155256

public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int num = in.nextInt();
        double s = Math.PI * Math.pow(num, 2);
        String format = String.format("%.6f", s);
        System.out.println(format);
    }
}

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