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Chef and Strange Operations ALL SUBMISSIONS Problem code: STROPR Tweet

https://www.codechef.com/FEB16/problems/STROPR 1/3 2/8/2016 Chef and Strange Operations | CodeChef

Read problems statements in Mandarin Chinese, Russian and Vietnamese as SUCCESSFUL SUBMISSIONS  well.

Chef has an array A consisting of N integers (1­based indexing). He asks you to perform the following operation M times: for i = 2 to N: Ai = Ai + Ai­1 th Your task is to find the x element of the array (i.e., Ax) after performing the above operation M times. As the answer could be large, please output it modulo 109 + 7. Input

The first line of input contains an integer T denoting the number of test cases. The first line of each test case contains three space­separated integers — N, x, and M — denoting the size of the array, index of the element you need to find, and the amount of times you need to repeat operation before finding the element, respectively. The second line contains N space­separated integers A1, A2, …, AN. Output

9 For each test case, output a single line containing one integer: Ax modulo 10 + 7. Constraints

1 ≤ T ≤ 10 1 ≤ x ≤ N ≤ 105

1 ≤ M ≤ 1018

1 ≤ A ≤ 1018 i Subtasks

Subtask 1 (8 points):

1 ≤ x ≤ min{2, N}

Subtask 2 (24 points):

1 ≤ N * M ≤ 106

Subtask 3 (68 points): No additional constraints Example

Input: 2 3 2 3 1 2 3 3 3 3 1 2 3

Output: 5 15 Explanation

Values in the array A:

Before the operations: [1, 2, 3] After the first operation: [1, 3, 6] After the second operation: [1, 4, 10] After the third operation: [1, 5, 15]

Since input file can be fairly large (about 8 MB), it's recommended to use fast I/O (for example, in ++, use scanf/printf instead of cin/cout).

Author: antoniuk1

Tester: iscsi

Date Added: 23­01­2015

Time Limit: 2 sec

Source Limit: 50000 Bytes

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