Trapping Rain Water Problem Statement

Given a long type array/list ARR of size N, representing an elevation map where ARR[i] denotes the elevation of the ith bar, calculate the total amount of rainwater that can be trapped in these elevations.

Input:

The first line contains an integer 'T' denoting the number of test cases. Following this, the test cases are provided:

For each test case:
 - The first line contains an integer 'N', representing the size of the array/list.
 - The second line contains 'N' space-separated integers representing the elevation of the bars.

Output:

For each test case, output a single integer in a separate line, indicating the total water that can be trapped.

Example:

Input:
2
6
0 1 0 2 1 0
3
3 0 2
Output:
1
1

Constraints:

• 1 ≤ T ≤ 10
• 0 ≤ N ≤ 10^4
• 0 ≤ ARR[i] ≤ 10^9

Note:

The width of each bar is the same and is equal to 1.
You do not need to print anything explicitly. Implement the function to return the result.