HDU-2123 Calculate the formula

Calculate the formula

Time Limit: 1000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 3836    Accepted Submission(s): 1126

Problem Description

You just need to calculate the sum of the formula: 1^2+3^2+5^2+……+ n ^2.

 

Input

In each case, there is an odd positive integer n.

 

Output

Print the sum. Make sure the sum will not exceed 2^31-1

 

Sample Input

3

 

Sample Output

10

 

　　这题首先是测出了他到2 ^31-1时N是多少。2344就溢出了，只要算到2343即可。  噼里啪啦敲完了，可是排名实在靠后，输入外挂，对，这时好东西。但是这题又有点不好处理 ，那就是出入数据是要来判定是否已经读到文件结尾，熟悉了scanf这个函数可以用 == EOF来判定是否结束，其实getchar也能够用来判定是否结尾。。。

　　代码如下：

#include <cstdio>
#include <cstring>
#include <cstdlib>
using namespace std;

int rec[2345];

bool getint( int &t )
{
    char c;
    while( c = getchar(), c < '0' || c > '9' ) 
    {
        if( c == EOF )
            return false;
    }
    t = c - '0';
    while( c = getchar(), c >= '0' && c <= '9' )
        t = t * 10 + c - '0';
    return true;
}

int main()
{
    rec[1] = 1;
    for( int i = 3; i <= 2343; i += 2 )
    {
        rec[i] = rec[i-2] + i * i;
    }
    int N;
    while( getint( N ) )
    {
        printf( "%d\n", rec[N] );
    }
    return 0;
}