Asher The King

 Profile Answers by Asher The King 

• Jul 10th, 2011

 

int sum=0;
For (int i=0;i<Line;i++)
    For(int j=0;j<COL;j++)
    {
         //Primary diagonal
         if(i==j )sum += A[i][j];
         //Secondary diagonal
         if(i==(COL-j))sum += A[i][j];
     }

Ashima

• Aug 9th, 2012

 

Assuming the matrix size is row, col and i represents the row and j represents the col.
Get the primary Diagonal where i==j and secondary diagonal where i==j-1.
Below is the code for that.

Code
for (int i = 0; i < row; i++)


            {


                int j = 0;


                while (j < col)


                {


                    //Primary diagonal


                    if (i == j) sum += A[i][j];


                    j++;


                    //Secondary diagonal


                    if (i == (col - j)) sum += A[i][j - 1];


                }


            }

JosephVP

• Jul 24th, 2014

 

As it is a Square Matrix, we can do with single Loop, Please follow the below algorithm.

Code
private static void findSumOfPrimaryAndSecondaryDiagonal(int[][] sortedMatrix, int rowStartPos, int columnStartPos){


                int sumValuePrimary = 0;


                int sumValueSecondaryRight= 0;


                int sumValueSecondaryLeft= 0;


                for(int i=0;i<=rowStartPos;i++){


                        sumValuePrimary += sortedMatrix[i][i];


                        if(i!=rowStartPos){


                                sumValueSecondaryRight+=sortedMatrix[i][i+1];


                        }


                        if(i!=0){


                                sumValueSecondaryLeft+=sortedMatrix[i][i-1];


                        }


                }


                System.out.println("Primary Total Is : "+sumValuePrimary+", Secondary Left Total Is : "+sumValueSecondaryLeft+", Secondary Right Total Is : "+sumValueSecondaryRight);


        }

hema

• Jan 3rd, 2015

 

Code
package testCode;


 


public class SquareMatrix {


        


 


        public static void main(String[] args) {


        int [][] squarematrix =  {


                      { 1,1,1,10},


                      { 1,10,-1,2},


                      { 1,-2,1,2},


                      { 1,1,1,-2}


                    };


        int primryDiagonaSum = 0, secondaryDiagonalSum = 0;


        int size = squarematrix.length -1;


        for(int i = 0; i<squarematrix.length; i++){


                primryDiagonaSum += squarematrix[i][i];


                secondaryDiagonalSum+= squarematrix[i][size-i];


        }


        System.out.println(" Primary diagonal sum =" +primryDiagonaSum);


        System.out.println(" Secondary diagonal sum =" + secondaryDiagonalSum);


        }


        }


 

hema

• Jan 3rd, 2015

 

Tested Java code

Code
package testCode;


 


public class SquareMatrix {


        public static void main(String[] args) {


        int [][] squarematrix =  {


                      { 1,1,1,10},


                      { 1,10,-1,2},


                      { 1,-2,1,2},


                      { 1,1,1,-2}


                    };


        int primryDiagonaSum = 0, secondaryDiagonalSum = 0;


        int size = squarematrix.length -1;


        for(int i = 0; i<squarematrix.length; i++){


                primryDiagonaSum += squarematrix[i][i];


                secondaryDiagonalSum+= squarematrix[i][size-i];


        }


        System.out.println(" Primary diagonal sum =" +primryDiagonaSum);


        System.out.println(" Secondary diagonal sum =" + secondaryDiagonalSum);


        }


        }


 

Kavya oleti

• Jan 22nd, 2017

 

If it is a square matrix order n
Primary diagonal
if(i==j)
{
sum+=a[i][j];
}
Secondary diagonal
if(i==(n-1)-j)
{
sum+=a[i][j];
}