PROBLEM DESCRIPTION
Given a NxM 2-D matrix, the task to find the sum of all the submatrices.
SOLUTION
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import java.io.*;
class GFG {
public static int matrixSum(int[][] matrix){
int n = matrix.length;
int m = matrix[0].length;
int totalSum = 0;
for(int i=0; i<n; i++){
for(int j=0; j<m; j++){
int topLeft = (i+1) * (j+1);
int bottomRight = (n-i) * (m-j);
int times = topLeft * bottomRight;
int contribution = times * matrix[i][j];
totalSum += contribution;
}
}
return totalSum;
}
}