洛谷 P5708、P5714、P5720、P5725、P5726、P5732、P5738 题解

P5708 题目要求

P5708题目链接

P5708 AC代码（Java语言描述）

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        double a = scanner.nextDouble(), b = scanner.nextDouble(), c = scanner.nextDouble(), p = (a+b+c)/2;
        System.out.printf("%.1f", Math.sqrt(p*(p-a)*(p-b)*(p-c)));
        scanner.close();
    }
}

P5714 题目要求

P5714题目链接

P5714 AC代码（Java语言描述）

import java.util.Scanner;

public class Main {

    /**
     * 有效数字
     */
    private static double roundToSignificantFigures(double num, int n) {
        if(num == 0) {
            return 0;
        }
        double d = Math.ceil(Math.log10(Math.abs(num)));
        int power = n - (int) d;
        double magnitude = Math.pow(10, power);
        long shifted = Math.round(num*magnitude);
        return shifted/magnitude;
    }

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        double result = roundToSignificantFigures(scanner.nextDouble()/Math.pow(scanner.nextDouble(), 2), 6);
        scanner.close();
        if (result