Maximum prefix sum for a given range
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  Difficulty: Easy
       

Given an array of n integers and q queries, each query having a range from l to r. Find the maximum prefix-sum for the range l to r.
NOTE: Assume indexing from 0.

Input: a[] = {-1, 2, 3, -5} 
       q = 2
       l = 0, r = 3
       l = 1, r = 3

Output: 4
        5

Explanation:- The range (0, 3) in the 1st query has
              [-1, 2, 3, -5], since it is prefix, 
              we have to start from -1. Hence, the 
              max prefix sum will be -1 + 2 + 3 = 4.
              The range (1, 3) in the 1st query has 
              [2, 3, -5], since it is prefix, we 
              have to start from 2. Hence, the max
              prefix sum will be 2 + 3 = 5.

Input:
The first line consists of an integer T i.e number of test cases. The first line of each test case consists of two integers n and q.Then next line consists of n spaced integers. The last line of each test case consists of q pairs of integers representing l and r.

Output:
Print the required answer.

Constraints: 
1<=T<=100
1<=n,q,a[i]<=104

Example:
Input:

2
4 2
-1 2 3 -5
0 3 1 3
8 1
-2 -3 4 -1 -2 1 5 -3
1 7

Output:
4 5
4

** For More Input/Output Examples Use 'Expected Output' option **

Contributor: Saksham Ashtputre
Author: saksham0751


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