Watch 10 video solutions for Matrix Diagonal Sum, a easy level problem involving Array, Matrix. This walkthrough by Knowledge Center has 22,800 views views. Want to try solving it yourself? Practice on FleetCode or read the detailed text solution.
Given a square matrix mat, return the sum of the matrix diagonals.
Only include the sum of all the elements on the primary diagonal and all the elements on the secondary diagonal that are not part of the primary diagonal.
Example 1:
Input: mat = [[1,2,3], [4,5,6], [7,8,9]] Output: 25 Explanation: Diagonals sum: 1 + 5 + 9 + 3 + 7 = 25 Notice that element mat[1][1] = 5 is counted only once.
Example 2:
Input: mat = [[1,1,1,1], [1,1,1,1], [1,1,1,1], [1,1,1,1]] Output: 8
Example 3:
Input: mat = [[5]] Output: 5
Constraints:
n == mat.length == mat[i].length1 <= n <= 1001 <= mat[i][j] <= 100