'GRID' = [ [1, 2, 3],
[4, 5, 6],
[7, 8, 9] ]
'Q' = 1, left corner = (1, 1), right corner = (2, 2)
submatrix = [ [5, 6],
[8, 9] ]
Answer = 28
The first line of input contains an integer 'T’ denoting the number of test cases to run. Then the test case follows.
The first line of each test case contains three space-separated integers ‘N’, ‘M’, ‘Q’ number of rows and number of columns in 'GRID' and number of queries.
Then ‘N’ lines follow. Each of the lines contains ‘M’ space-separated integers denoting the elements of the matrix 'GRID'.
Then ‘Q’ lines follow. Each of the lines contains four space-separated integers ‘X1’, ‘Y1’, ‘X2’, ‘Y2’ where (‘X1’, ‘Y1’) is an upper left corner. (‘X2’, ‘Y2’) is the lower right corner.
For each test case, return the array that contains sum of elements in the submatrix defined by the upper left and lower right corner for each query.
You don’t need to print anything. It has already been taken care of. Just implement the given function.
1 <= T <= 5
1 <= N, M <= 10^3
-10^4 <= GRID[i][j] <= 10^4
Time Limit: 1 sec
We will iterate over the subgrid and calculate the sum of all elements in this subgrid of each query.
The algorithm will be-
We will precompute the sum of the submatrix that has the upper left corner fixed at (0, 0) and represent the required submatrix as a combination of computed submatrixes.
The algorithm will be-
Eg. rectangular subgrid from (1,1) to (2,2) can be represented as.
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