Paper folding

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 416    Accepted Submission(s): 45

Problem Description

Mr.Hu was addicted to games about paper.Now he has a square paper,then he fold the paper along the midline for N times,and the latter fold and the former fold are vertical.Eventually ,the paper will be divided into a certain number of grids by the fold.Now,Give you the minimum length K of the grid.Can you tell me the area of the paper?
(the answer mod 10000007 )

 

Input

There are multiple of cases.Each case in a line.Each line will contain two integers N and K(0=<N<=10^9,0<K<1000).

 

Output

Output the answer in a line.

 

Sample Input

1 22 34 6

 

Sample Output

1636576
#include <stdio.h>

int main()
{
    int n,k;
    __int64 a,b;
    while(scanf("%d %d",&n,&k)!=EOF)
    {
        a=1,b=2;
        if(n%2!=0)
            n++;
        while(n>0)
        {
            if(n%2!=0)
                a=(a*b)%10000007;
            b=(b*b)%10000007;
            n=n/2;
        }
        k=(k*k)%10000007;
        printf("%I64d\n",(a*k)%10000007);
    }
    return 0;
}
题意就是给你折叠的次数和一个边的长度，求原来纸的面积
这道题关键是对偶数次的还原，为什么我对每一步都取余呢，嘿嘿，因为我怕数太大