华为在线编程题系列-7-取近似值

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问题描述:

1. 问题涉及知识点.

浮点型的向上取整和向下取整.
Math.ceil(key)向上取整 5.6 –> 6
Math.floor(key)向下取整 5.6 –> 5

2. 自己解法.

• 拿到小数点后一位key*10%10 .

package com.chaoxiong.niuke.huawei;
import java.util.Scanner;
/**
 * Create by tianchaoxiong on 18-4-8.
 */
public class HuaWei_7 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        while (scanner.hasNext()) {
            float in = scanner.nextFloat();
            int key = (int) (in*10)%10;
            if(key<5)
                System.out.println((int)Math.floor(in));
            else
                System.out.println((int)Math.ceil(in));
        }
    }
}

3. 优质答案.

null

4. 本题总结.

Math.ceil(key)向上取整 5.6 –> 6
Math.floor(key)向下取整 5.6 –> 5

public static double abs(double a),               --------------abs方法求绝对值
public static native double acos(double a)        -------------acos求反余弦函数
public static native double asin(double a)        -------------asin求反正切函数
public static native double atan(double a)        -------------atan求反正切函数
public static native double ceil(double a)        -------------ceil返回值最小的大于a的整数
public static native double cos(double a)        -------------cos求余弦函数
public static native double exp(double a)        -------------exp求e的a次幂
public static native double floor(double a)        -------------floor返回最大的小于a的数
public static native double log(double a)        -------------log返回lna
public static native double pow(double a，double b)------pow求a的b次幂
public static native double sin(double a)        -------------sin求正弦函数
public static native double sqrt(double a)      -------------sqrt求a的开平方
public static native double tan(double a)      -------------tan求正切函数
public static synchronized double random() -------------返回0~1的随机数