了解Math函数

using System;

public class Evaporator { 
  
  public static int evaporator(double content, double evap_per_day, double threshold) {

    return (int)Math.Ceiling(Math.Log(threshold / 100.0) / Math.Log(1.0 - evap_per_day / 100.0));
  }
}

/*
1,Math.Ceilling（向上取整）
2,Math.Log 取对数 lne=1
http://www.cnblogs.com/yuruolt/p/4561838.html（【Math类】常用函数)
*/

public class Evaporator { 
    public static int evaporator(double content, double evap_per_day, double threshold)
    {
        content = 100.0;
        int days = 0;
        while (content > threshold)
        {
            content -= content * evap_per_day * .01;
            days += 1;
        }
//每天都比较下总内容和每天要散发出的，需要22天才能挥发完。
        return days;
    }
}