CSUFT OJ 1142 及 1141_the senior wanted you to create a water problem.th-优快云博客

本文链接：https://blog.youkuaiyun.com/OneLine_/article/details/80392236

本文介绍了两道关于计算正弦和余弦值的题目。通过使用字符数组存储大数并运用数学库函数进行计算，解决了数据超出常规整型变量范围的问题。

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想把两道题目一起写一下

就先说简单的1142

这道题目是 2017年度上学期第三次月赛的B题

1142: Real Small Water Problem

Time Limit: 1 Sec		Memory Limit: 128 MB
Submit: 37		Solved: 10

Description

The senior wanted you to create a water problem.This made you a headache.So you asked BingYu for help.Immediately after he listened,he came up with a problem:
Give you a positive integer n.
Function F_x satisfies:
F(0) = sinn
F(x) = sinF(x-1) (x>0)
Calculate F(n).

Input

The input contains no more than 20 test cases.
For each test case,the only line consists of one integer n.
0<=n<=100.

Output

For each given n,print the answer in a single line.The result should be rounded to six decimal places.

Sample Input

0
1
2

Sample Output

0.000000
0.745624
0.709700

HINT

sin函数在math.h头文件里。

例如算1的sin值

double ans=sin(1);

没啥好讲的感觉直接上代码（真 • 水题）

#include <iostream>
#include <math.h>
#include <stdio.h>
using namespace std;
int main()
{
    double m,t;
    int a;
    while(~scanf("%d",&a))
    {
      m=sin(a);
      for (int i=0;i<a;i++)
        m=sin(m);
      t=m;
        printf("%.6lf\n",t);
    }
    return 0;
}

下面讲一下 1141

这题作为校赛热身赛的压轴题看到题目的时候就有印象

是2017年度上学期第三次月赛的C题当时没做出来后来补题了

但是忘记数据如何处理了

想了很久才想出来...

1141: Real Big Water Problem

Time Limit: 1 Sec		Memory Limit: 128 MB
Submit: 65		Solved: 20

Description

If you have solved the small water problem,let's see this big one.If you don't,I suggest you ignore this problem!

Also give you a positive integer n.

Function F_x satisfies:

F(0) = cos n

F(x) = cos F(x-1) (x>0)

Calculate F(n).

Input

The input contains no more than 20 test cases.

For each test case,the only line consists of one integer n.

0 <= n <= 10^30.

Output

For each given n,print the answer in a single line.The result should be rounded to six decimal places.

Sample Input

0
1
2

Sample Output

1.000000
0.857553
0.610065

HINT

cos函数在math.h头文件里。

例如：计算1的cos值：double ans=cos(1);

注意：这个题的数据范围

这题的数据特别大用 long long 都存不下这么大的数据

所以考虑用 字符数组 读入然后再用 atoi 函数将字符转化为数字

其次打表看一下数据是有规律的

从 n=35 开始 输出结果不变恒为 0.739085

放一下代码：

#include <stdio.h>
#include <iostream>
#include <algorithm>
#include <math.h>
#include <string.h>
using namespace std;
char a[105];
double x[105];
void f(int n)
{
    x[0]=cos(n);
    for (int i=1; i<100; i++)
        x[i]=cos(x[i-1]);
}
int main()
{
    int n;
    while (~scanf("%s",a))//10的30次方太大 用字符数组存
    {
        memset(x,0,sizeof x);
        if (strlen(a)>=3)
        {
            printf("0.739085\n");
            continue;
        }
        else if (strlen(a)<3)
           n=atoi(a);//将char转化成int
        if (n<40)//数据有规律 n>35时x[n]的大小不变 为定值
        {
            f(n);
            printf("%lf\n",x[n]);
        }
        else printf("0.739085\n");
    }
    return 0;
}

注：sin（）和 cos（）都在 math.h 的头文件里

数据太大存不了时要考虑以别的形式存储数据