Sum it up
题目连接：
https://www.hackerrank.com/contests/ieeextreme-challenges/challenges/sum-it-up
Description
Minka is very smart kid who recently started learning computer programming.
His coach gave him a cyclic array A having N numbers, and he has to perform Q operations on this array.
In each operation the coach would provide him with a number X. After each operation, every element of the cyclic array would be replaced by the sum of itself and the element lying X positions behind it in the cyclic array. All these replacements take place simultaneously.
For example, if the cyclic array was [a, b, c, d], then after the operation with X = 1, the new array would be [a+d, b+a, c+b, d+c].
He needs to output the sum of the elements of the final array modulus 10^9+7.
He made a program for it but it's not very efficient. You know he is a beginner, so he wants you to make an efficient program for this task because he doesn't want to disappoint his coach.
Input
The first line of each test file contains a integer N (1 <= N <= 100000).
The next line contains N space separated integers which represent the elements of the cyclic array ( 1 <= Ai <= 10^9 ).
The third line contains a integer Q (0 <= Q <= 1000000) representing the number of operations that will be applied to the array.
Finally, Q lines follow, each one containing an integer X (0 <= X < N).
Output
Your program should output to the standard output stream the sum of the elements of the final array modulus 10^9+7.
Note: There is a newline character at the end of the last line of the output.
Sample Input
5
1 2 3 4 5
2
1
0
Sample Output
60
Hint
题意
给你n个数，然后有Q次操作
每次操作是让a[i]+=a[(i+x)%n]
最后问你所有数的和是多少
题解
一个个去想的话，感觉不可做
但是你从整体去思考的话，那么显然就是一个傻逼题了。
代码
#include<bits/stdc++.h>
using namespace std;
const int maxn = 1e5+7;
const int mod = 1e9+7;
int a[maxn];
int main()
{
int n,m;scanf("%d",&n);
long long ans = 0,sum = 0;
for(int i=1;i<=n;i++)
{
scanf("%d",&a[i]);
sum+=a[i],sum%=mod;
}
scanf("%d",&m);
for(int i=1;i<=m;i++){
int x;
scanf("%d",&x);
sum=(sum+sum)%mod;
}
cout<<sum<<endl;
}