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[Java] 蓝桥杯ADV-83 算法提高寻找三位数

问题描述
将1，2，…，9共9个数分成三组，分别组成三个三位数，且使这三个三位数构成
1：2：3的比例，试求出所有满足条件的三个三位数。
例如：三个三位数192，384，576满足以上条件。
输入格式
无输入文件
输出格式
输出每行有三个数，为满足题设三位数。各行为满足要求的不同解。

package adv83;

import java.util.Scanner;

public class Main {

    private static int[] num;
    
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        num = new int[9];
        in.close();
        dfs(0);
    }

    private static void dfs(int pos) {
        if (pos == 9) {
            int one = num[0] * 100 + num[1] * 10 + num[2];
            int two = num[3] * 100 + num[4] * 10 + num[5];
            int three = num[6] * 100 + num[7] * 10 + num[8];
            
            if (one * 2 == two && one * 3 == three) {
                System.out.println(one + " " + two + " " + three);
            }
            
            return;
        }
        
        for (int i = 1; i <= 9; i++) {
            if (isNotSelect(pos, i)) {
                num[pos] = i;
                dfs(pos + 1);
            }
        }
    }
    
    private static boolean isNotSelect(int pos, int value) {
        for (int i = 0; i < pos; i++) {
            if (num[i] == value) {
                return false;
            }
        }
        return true;
    }

}

package adv83;

import java.util.Scanner;

public class Main {

private static int[] num;

public static void main(String[] args) {

Scanner in = new Scanner(System.in);

num = new int[9];

in.close();

dfs(0);

}

private static void dfs(int pos) {

if (pos == 9) {

int one = num[0] * 100 + num[1] * 10 + num[2];

int two = num[3] * 100 + num[4] * 10 + num[5];

int three = num[6] * 100 + num[7] * 10 + num[8];

if (one * 2 == two && one * 3 == three) {

System.out.println(one + " " + two + " " + three);

}

return;

}

for (int i = 1; i <= 9; i++) {

if (isNotSelect(pos, i)) {

num[pos] = i;

dfs(pos + 1);

}

private static boolean isNotSelect(int pos, int value) {

for (int i = 0; i < pos; i++) {

if (num[i] == value) {

return false;

}

return true;

}

[Java] 蓝桥杯ADV-85 算法提高算术运算

编写一程序，接受用户输入的两个整数，并计算它们的和、差、
积、商，程序运行时候输入输出例子如下所示。
样例输入：
3 5
样例输出：
3+5=8
3-5=-2
3*5=15
3/5=0
注意：输出要严格按照+-*/的顺序，分四行输出，而且中间不能有空格，否则系统会判为错误。

package adv85;

import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int a = in.nextInt();
        int b = in.nextInt();
        in.close();
        System.out.println(a + "+" + b + "=" + (a + b));
        System.out.println(a + "-" + b + "=" + (a - b));
        System.out.println(a + "*" + b + "=" + (a * b));
        System.out.println(a + "/" + b + "=" + (a / b));
    }

}

package adv85;

import java.util.Scanner;

public class Main {

public static void main(String[] args) {

Scanner in = new Scanner(System.in);

int a = in.nextInt();

int b = in.nextInt();

in.close();

System.out.println(a + "+" + b + "=" + (a + b));

System.out.println(a + "-" + b + "=" + (a - b));

System.out.println(a + "*" + b + "=" + (a * b));

System.out.println(a + "/" + b + "=" + (a / b));

}

[Java] 蓝桥杯ADV-91 算法提高素数判断

编写一函数IsPrime，判断某个大于2的正整数是否为素数。
样例输入:
5
样例输出:
yes
样例输入:
9
样例输出:
no
注意：是素数输出yes，不是素数输出no，其中yes和no均为小写。

package adv91;

import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        in.close();
        if (isPrime(n)) {
            System.out.println("yes");
        } else {
            System.out.println("no");
        }
    }
    
    private static boolean isPrime(int num) {
        for (int i = 2; i < num; i++) {
            if (num % i == 0) {
                return false;
            }
        }
        
        return true;
    }

}

package adv91;

import java.util.Scanner;

public class Main {

public static void main(String[] args) {

Scanner in = new Scanner(System.in);

int n = in.nextInt();

in.close();

if (isPrime(n)) {

System.out.println("yes");

} else {

System.out.println("no");

}

private static boolean isPrime(int num) {

for (int i = 2; i < num; i++) {

if (num % i == 0) {

return false;

}

return true;

}

[Java] 蓝桥杯ADV-92 算法提高求最大公约数

编写一函数gcd，求两个正整数的最大公约数。
样例输入:
5 15
样例输出:
5
样例输入:
7 2
样例输出:
1

package adv92;

import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        System.out.println(gcd(in.nextInt(), in.nextInt()));
        in.close();
    }

    private static int gcd(int a, int b) {
        if (b == 0) {
            return a;
        }
        return gcd(b, a % b);
    }
}

package adv92;

import java.util.Scanner;

public class Main {

public static void main(String[] args) {

Scanner in = new Scanner(System.in);

System.out.println(gcd(in.nextInt(), in.nextInt()));

in.close();

}

private static int gcd(int a, int b) {

if (b == 0) {

return a;

}

return gcd(b, a % b);

}

[Java] 蓝桥杯ADV-95 算法提高字符串比较

独立实现标准字符串库的strcmp函数，即字符串比较函数，从键盘输入两个字符串，按字典序比较大小，前者大于后者输出1，前者小于后者输出-1，两者相等输出0。
样例输入:
apple one
样例输出:
-1
样例输入:
hello he
样例输出:
1
样例输入:
hello hello
样例输出:
0

package adv95;

import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        String a = in.next();
        String b = in.next();
        in.close();
        if (a.compareTo(b) < 0) { System.out.println("-1"); } else if (a.compareTo(b) > 0) {
            System.out.println(1);
        } else {
            System.out.println(0);
        }
    }

}

package adv95;

import java.util.Scanner;

public class Main {

public static void main(String[] args) {

Scanner in = new Scanner(System.in);

String a = in.next();

String b = in.next();

in.close();

if (a.compareTo(b) < 0) { System.out.println("-1"); } else if (a.compareTo(b) > 0) {

System.out.println(1);

} else {

System.out.println(0);

}

[Java] 蓝桥杯ADV-96 算法提高复数求和

从键盘读入n个复数（实部和虚部都为整数）用链表存储，遍历链表求出n个复数的和并输出。
样例输入:
3
3 4
5 2
1 3
样例输出:
9+9i
样例输入:
7
1 2
3 4
2 5
1 8
6 4
7 9
3 7
样例输出:
23+39i

package adv96;

import java.util.Scanner;

public class Main {

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

}

package adv96;

import java.util.Scanner;

public class Main {

public static void main(String[] args) {

Scanner in = new Scanner(System.in);

int n = in.nextInt();

int a = 0;

int b = 0;

for (int i = 0; i < n; i++) {

a += in.nextInt();

b += in.nextInt();

}

in.close();

System.out.println(a + "+" + b + "i");

}