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：

 1 #include <cstdio>
 2 #include <cstring>
 3 #include <cstdlib>
 4 using namespace std;
 5 
 6 int rec[2345];
 7 
 8 bool getint( int &t )
 9 {
10     char c;
11     while( c = getchar(), c < '0' || c > '9' ) 
12     {
13         if( c == EOF )
14             return false;
15     }
16     t = c - '0';
17     while( c = getchar(), c >= '0' && c <= '9' )
18         t = t * 10 + c - '0';
19     return true;
20 }
21 
22 int main()
23 {
24     rec[1] = 1;
25     for( int i = 3; i <= 2343; i += 2 )
26     {
27         rec[i] = rec[i-2] + i * i;
28     }
29     int N;
30     while( getint( N ) )
31     {
32         printf( "%d\n", rec[N] );
33     }
34     return 0;
35 }