Java 第十四届蓝桥杯三月真题刷题训练——第 2 天

[Feishi11]

第一题：奇数倍数

public class Main{
    public static void main(String[] args) {
        int n = 2019;
        for (int i = 2; i <= Integer.MAX_VALUE; i++) {
            long tmp = (long) n * i;
            if (check(tmp)) {
                System.out.println(tmp);
                break;
            }
        }
    }

    static boolean check(long tmp) {
        while (tmp > 0) {
            long sum = tmp % 10;
            tmp /= 10;
            if ((sum & 1) != 1) {
                return false;
            }
        }
        return true;
    }
}

第二题：求值

public class Main{
    public static void main(String[] args) {
        for (int k = 100; k <= Integer.MAX_VALUE; k++) {
            int max = 1;
            int n = k;
            for (int i = 2; i <= n / i; i++) {
                int count = 0;
                while (n % i == 0) {
                    count++;
                    n /= i;
                }
                max *= (count + 1);
            }
            if (n > 1) {
                max <<= 1;
            }
            if (max == 100) {
                System.out.println(k);
                return;
            }
        }
    }
}

第三题：求和

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {
    static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

    public static void main(String[] args) throws IOException {
        int n = Integer.parseInt(br.readLine());
        String[] s = br.readLine().split(" ");
        long ans = 0, ans1 = 0;
        for (int i = 1; i <= n; i++) {
            int x = Integer.parseInt(s[i - 1]);
            ans += x * x;
            ans1 += x;
        }
        System.out.println((ans1 * ans1 - ans) / 2);
    }
}

第四题：数位排序

 

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Arrays;
import java.util.Comparator;

public class Main{
    static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

    public static void main(String[] args) throws IOException {
        int n = Integer.parseInt(br.readLine());
        Integer[] a = new Integer[n + 1];
        for (int i = 1; i <= n; i++) {
            a[i] = i;
        }
        Arrays.sort(a, 1, n + 1, (o1, o2) -> {
            int tmp = get(o1);
            int tmp2 = get(o2);
            if (tmp > tmp2) {
                return 1;
            } else if (tmp < tmp2) {
                return -1;
            }
            return o1 - o2;

        });
        int m = Integer.parseInt(br.readLine());
        System.out.println(a[m]);
    }

    public static int get(int x) {
        int sum = 0;
        while (x > 0) {
            sum += x % 10;
            x /= 10;
        }
        return sum;
    }
}