Write a program to Find sum of lower triangle in matrix.
Sum of lower triangle = 1+5+6+8+7+6+4+3+2+1= 43
Logic behind finding sum of lower triangle in matrix is:
//Logic to calculate sum of lower triangle.
int sum=0;
for (int i = 0; i < rows; i++) {
for (int j=i ; j>=0 ; j--) {
sum= sum + matrix[i][j];
}
}
Full Program/SourceCode >
package matrix;
import java.util.Scanner;
/** Copyright (c), AnkitMittal JavaMadeSoEasy.com */
public class SumOfLowerTriangle {
public static void main(String...args) {
Scanner scanner = new Scanner(System.in);
System.out.print("Enter number of rows/columns in matrix : "); //rows and columns in matrix must be same.
int rows = scanner.nextInt();
int columns=rows;
int[][] matrix = new int[rows][rows];
System.out.println("Enter the elements in matrix :");
for (int i = 0; i < rows; i++) {
for (int j = 0; j < columns; j++) {
matrix[i][j] = scanner.nextInt();
}
}
//Logic to calculate sum of lower triangle.
int sum=0;
for (int i = 0; i < rows; i++) {
for (int j=i ; j>=0 ; j--) {
sum= sum + matrix[i][j];
}
}
System.out.println("\nMatrix is : ");
for (int i = 0; i < rows; i++) {
for (int j = 0; j < columns; j++) {
System.out.print(matrix[i][j] + " ");
}
System.out.println();
}
System.out.println("sum of lower triangle is: "+sum);
}
}
/*OUTPUT
Enter number of rows/columns in matrix : 4
Enter the elements in matrix :
1
2
3
4
5
6
7
8
8
7
6
5
4
3
2
1
Matrix is :
1 2 3 4
5 6 7 8
8 7 6 5
4 3 2 1
sum of lower triangle is: 43
*/
|
RELATED LINKS>
>Pattern/Pyramid generating programs
Labels:
Core Java
Matrix programs