Easy Accuracy: 32.13% Submissions: 28 Points: 2

Given a matrix Arr of size N x M. You are given position of submatrix as X1, Y1 and X2, Y2 inside the matrix. Find the sum of all elements inside that submatrix. Here X1, Y1, X2, Y2 are 1-based.

Example 1:

Input:
N = 5 , M = 6
Arr[][] = {{1, 2, 3, 4, 5, 6},
{7, 8, 9, 10, 11, 12},
{13, 14, 15, 16, 17, 18},
{19, 20, 21, 22, 23, 24},
{25, 26, 27, 28, 29, 30}}
X1=3, Y1=4, X2=4, Y2=5
Output: 78
Explanation: Sum from cell starting at
position (3, 4) (1-based indexing) and
ending at (4, 5) is 78.


Example 2:

Input:
N = 3, M = 3
Arr[][] = {{9, 8, 7},{4, 2, 1},{6, 5, 3}}
X1=1, Y1=2, X2=3, Y2=3
Output: 1
Explanation: Sum from cell starting at
position (1, 2) (1-based indexing) and
ending at (3, 3) is 26.


You don't need to read input or print anything. Your task is to complete the function subMatrixSum() which takes the array of booleans arr[][], n, m, x1, y1, x2 and y2 as parameters and returns an integer denoting the answer.

Expected Time Complexity: O(N*M)
Expected Auxiliary Space: O(1)

Constraints:
1 ≤ N, M ≤ 103
1 ≤ Arr[N][M] ≤ 106
1 <= X1, X<= N
1 <= Y1, Y<= M