KConcatenation

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You are given an array A with size N (indexed from 0) and an integer K. Let's define another array B with size N · K as the array that's formed by concatenating K copies of array A.
For example, if A = {1, 2} and K = 3, then B = {1, 2, 1, 2, 1, 2}.
You have to find the maximum subarray sum of the array B. Fomally, you should compute the maximum value of B_{i} + B_{i+1} + B_{i+2} + ... + B_{j}, where 0 ≤ i ≤ j < N · K.
Input
 The first line of the input contains a single integer T denoting the number of test cases. The description of T test cases follows.
 The first line of each test case contains two spaceseparated integers N and K.
 The second line contains N spaceseparated integers A_{0}, A_{1}, ..., A_{N1}.
Output
For each test case, print a single line containing the maximum subarray sum of B.
Constraints
 1 ≤ T ≤ 10
 1 ≤ N ≤ 10^{5}
 1 ≤ K ≤ 10^{5}
 10^{6} ≤ A_{i} ≤ 10^{6} for each valid i
Subtasks
Subtask #1 (18 points): N · K ≤ 10^{5}
Subtask #2 (82 points): original constraints
Example
Input: 2 2 3 1 2 3 2 1 2 1 Output: 9 2
Explanation
Example case 1: B = {1, 2, 1, 2, 1, 2} and the subarray with maximum sum is the whole {1, 2, 1, 2, 1, 2}. Hence, the answer is 9.
Example case 2: B = {1, 2, 1, 1, 2, 1} and the subarray with maximum sum is {1, 1}. Hence, the answer is 2.
Author:  hruday968 
Editorial  https://discuss.codechef.com/problems/KCON 
Tags  easy, hruday968, hruday968, jan18 
Date Added:  28122017 
Time Limit:  1 sec 
Source Limit:  50000 Bytes 
Languages:  C, CPP14, JAVA, PYTH, PYTH 3.5, PYPY, CS2, PAS fpc, PAS gpc, RUBY, PHP, GO, NODEJS, HASK, rust, SCALA, swift, D, PERL, FORT, WSPC, ADA, CAML, ICK, BF, ASM, CLPS, PRLG, ICON, SCM qobi, PIKE, ST, NICE, LUA, BASH, NEM, LISP sbcl, LISP clisp, SCM guile, JS, ERL, TCL, kotlin, PERL6, TEXT, SCM chicken, CLOJ, FS 
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