P16714 [CodeChef] KCON
提高-
题目描述

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 Bi + Bi+1 + Bi+2 + ... + Bj, 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 space-separated integers N and K.
  • The second line contains N space-separated integers A0, A1, ..., AN-1.

-----Output-----
For each test case, print a single line containing the maximum subarray sum of B.

-----Constraints-----
- 1 ≤ T ≤ 10
- 1 ≤ N ≤ 105
- 1 ≤ K ≤ 105
- -106 ≤ Ai ≤ 106 for each valid i

-----Subtasks-----
Subtask #1 (18 points): N · K ≤ 105
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.

输入格式

见题面

输出格式

见题面

样例输入
['2', '2 3', '1 2', '3 2', '1 -2 1', '', '']
样例输出
['9', '2']