Home » Kotlin » Kotlin Programs » Kotlin Array Programs

Kotlin program to print lower triangular of a matrix

Here, we are going to learn how to print lower triangular of a given matrix in Kotlin programming language? Submitted by IncludeHelp, on May 06, 2020

Kotlin - Print lower triangular of a matrix

Given a matrix, we have to print its lower triangular.

Example:

Input:
matrix:
[2, 3, 5]
[6, 7, 8]
[9, 2, 1]

Output:
[2, 0, 0]
[6, 7, 0]
[9, 2, 1]

Program to print lower triangular of a matrix in Kotlin

package com.includehelp

import java.util.*

// Main function, Entry Point of Program
fun main(args: Array<String>) {

    //variable of rows and col
    val rows: Int
    val column: Int

    //Input Stream
    val scanner = Scanner(System.`in`)

    //Input no of rows and column
    print("Enter the number of rows and columns of matrix : ")
    rows   = scanner.nextInt()
    column = scanner.nextInt()

    if(rows!=column) {
        println("Matrix should be Square matrix , Rows and Col size must be Same !!")
        return
    }

    //Create Array
    val matrixA     = Array(rows) { IntArray(column) }

    //Input Matrix
    println("Enter the Elements of First Matrix ($rows X $column} ): ")
    for(i in matrixA.indices){
        for(j in matrixA[i].indices){
            print("matrixA[$i][$j]: ")
            matrixA[i][j]=scanner.nextInt()
        }
    }

    //print Matrix A
    println("Matrix A : ")
    for(i in matrixA.indices){
        println("${matrixA[i].contentToString()} ")
    }

    //get lower triangular of matrix
    for(i in matrixA.indices){
        for(j in matrixA[i].indices){
            if(j>i) matrixA[i][j]=0
        }
    }

    //print Matrix A
    println("Lower Triangular of Matrix : ")
    for(i in matrixA.indices){
        println("${matrixA[i].contentToString()} ")
    }
}

Output

Run 1:
Enter the number of rows and columns of matrix : 4
3
Matrix should be Square matrix , Rows and Col size must be Same
---
Run 2:
Enter the number of rows and columns of matrix : 3
3
Enter the Elements of First Matrix (3 X 3} ):
matrixA[0][0]: 2
matrixA[0][1]: 3
matrixA[0][2]: 5
matrixA[1][0]: 6
matrixA[1][1]: 7
matrixA[1][2]: 8
matrixA[2][0]: 9
matrixA[2][1]: 2
matrixA[2][2]: 1
Matrix A :
[2, 3, 5]
[6, 7, 8]
[9, 2, 1]
Lower Triangular of Matrix :
[2, 0, 0]
[6, 7, 0]
[9, 2, 1]