C program to find sum of upper triangular matrix

Write a C program to read elements in a matrix and find sum of upper triangular matrix. How to find sum of upper triangular matrix in C.

Example: If elements of the matrix are:
1 2 3
0 5 6
0 0 9

Sum of upper triangular matrix = 11

Required knowledge:

Basic C programming, For loop, Array, Matrix

Upper triangular matrix

Upper triangular matrix is a special type of square matrix whose all elements below main diagonal is zero.

Algorithm to find sum of upper triangular matrix:

Upper triangular matrix elements can be described as below image we need to find sum of elements inside red triangle.

We can easily find sum of all elements matrix A inside the red triangular area i.e.
sum = sum + A_ij (Where i<j).

Program:

/**
 * C program to find sum of upper triangular matrix
 */

#include <stdio.h>

int main()
{
    int A[3][3];
    int row, col, sum = 0;
    
    /*
     * Reads elements in matrix from user
     */
    printf("Enter elements in matrix of size 3x3: \n");
    for(row=0; row<3; row++)
    {
        for(col=0; col<3; col++)
        {
            scanf("%d", &A[row][col]);
        }
    }
    
    /*
     * Finds sum of upper triangular matrix
     */
    for(row=0; row<3; row++)
    {
        for(col=0; col<3; col++)
        {
            if(col>row)
            {
                sum += A[row][col];
            }
        }
    }

    printf("Sum of upper triangular matrix = %d", sum);

    return 0;
} 

Happy coding ;)