Print numbers in matrix diagonal pattern

0 0 6 minutes read

Given an integer N, the task is to print the given pattern.
Examples:

Input: 3
Output:
1 2 4 
3 5 7 
6 8 9

Input: 4
Output:
1 2 4 7 
3 5 8 11 
6 9 12 14 
10 13 15 16

Approach:

Create a matrix of size N X N which will store the pattern before printing.
Store the elements in the upper triangle of the pattern. As observed the row index increases by 1 and column index decreases by 1 as you move down the diagonal.
Once the upper triangle is completed then store the elements of the lower triangle in similar way as the upper triangle i.e. row index increases by 1 and column index decreases by 1 as you move down the diagonal.

Below is the implementation of the above approach:

C++

// C++ program to print the required pattern
#include <bits/stdc++.h>
using namespace std;
 
// Function to print the required pattern
void printPattern(int n)
{
    // arr[][] will store the pattern matrix
    int arr[n][n], k, i, j, p = 1, f;
 
    // Store the values for upper triangle
    // of the pattern
    for (k = 0; k < n; k++) {
        j = k;
        i = 0;
        while (j >= 0) {
            arr[i][j] = p;
            p++;
            i = i + 1;
            j = j - 1;
        }
    }
 
    // Store the values for lower triangle
    // of the pattern
    for (k = 1; k < n; k++) {
        i = k;
        j = n - 1;
        f = k;
        while (j >= f) {
            arr[i][j] = p;
            p++;
            i = i + 1;
            j = j - 1;
        }
    }
 
    // Print the pattern
    for (i = 0; i < n; i++) {
        for (j = 0; j < n; j++) {
            cout << arr[i][j] << " ";
        }
        cout << endl;
    }
}
 
// Driver code
int main()
{
    int n = 3;
 
    printPattern(n);
 
    return 0;
}

Java

// Java program to print the required pattern 
 
public class GFG{
 
    // Function to print the required pattern 
    static void printPattern(int n) 
    { 
        // arr[][] will store the pattern matrix 
        int arr[][] = new int[n][n] ;
        int k, i, j, p = 1, f ; 
     
        // Store the values for upper triangle 
        // of the pattern 
        for (k = 0; k < n; k++) { 
            j = k; 
            i = 0; 
            while (j >= 0) { 
                arr[i][j] = p; 
                p++; 
                i = i + 1; 
                j = j - 1; 
            } 
        } 
     
        // Store the values for lower triangle 
        // of the pattern 
        for (k = 1; k < n; k++) { 
            i = k; 
            j = n - 1; 
            f = k; 
            while (j >= f) { 
                arr[i][j] = p; 
                p++; 
                i = i + 1; 
                j = j - 1; 
            } 
        } 
     
        // Print the pattern 
        for (i = 0; i < n; i++) { 
            for (j = 0; j < n; j++) { 
                System.out.print(arr[i][j] + " ") ; 
            } 
            System.out.println() ;
        } 
    } 
     
    // Driver code 
    public static void main(String []args) 
    { 
        int n = 3; 
     
        printPattern(n); 
    } 
    // This code is contributed by Ryuga
 
}

Python3

# Python 3 program to print the
# required pattern
 
# Function to print the required pattern
def printPattern(n):
     
    # arr[][] will store the pattern matrix
    arr = [[0 for i in range(n)]
              for j in range(n)]
    p = 1
 
    # Store the values for upper 
    # triangle of the pattern
    for k in range(n):
        j = k
        i = 0
        while (j >= 0):
            arr[i][j] = p
            p += 1
            i = i + 1
            j = j - 1
     
    # Store the values for lower triangle
    # of the pattern
    for k in range(1, n, 1):
        i = k
        j = n - 1
        f = k
        while (j >= f):
            arr[i][j] = p
            p += 1
            i = i + 1
            j = j - 1
     
    # Print the pattern
    for i in range(0, n, 1):
        for j in range(0, n, 1):
            print(arr[i][j], end = " ")
         
        print("\n", end = "")
 
# Driver code
if __name__ == '__main__':
    n = 3
 
    printPattern(n)
 
# This code is contributed by
# Sanjit_Prasad

C#

// C# program to print the required pattern 
using System;
 
public class GFG{
 
    // Function to print the required pattern 
    static void printPattern(int n) 
    { 
        // arr[][] will store the pattern matrix 
        int [,]arr = new int[n,n] ;
        int k, i, j, p = 1, f ; 
     
        // Store the values for upper triangle 
        // of the pattern 
        for (k = 0; k < n; k++) { 
            j = k; 
            i = 0; 
            while (j >= 0) { 
                arr[i,j] = p; 
                p++; 
                i = i + 1; 
                j = j - 1; 
            } 
        } 
     
        // Store the values for lower triangle 
        // of the pattern 
        for (k = 1; k < n; k++) { 
            i = k; 
            j = n - 1; 
            f = k; 
            while (j >= f) { 
                arr[i,j] = p; 
                p++; 
                i = i + 1; 
                j = j - 1; 
            } 
        } 
     
        // Print the pattern 
        for (i = 0; i < n; i++) { 
            for (j = 0; j < n; j++) { 
                Console.Write(arr[i,j] + " ") ; 
            } 
            Console.WriteLine() ;
        } 
    } 
     
    // Driver code 
    public static void Main() 
    { 
        int n = 3; 
     
        printPattern(n); 
    } 
    // This code is contributed by inder_verma..
 
}

PHP

<?php
// PHP program to print the required pattern 
 
// Function to print the required pattern 
function printPattern($n) 
{ 
    // arr[][] will store the pattern matrix 
    $arr[][] = array($n, $n);
    $k; $i; $j; $p = 1; $f; 
 
    // Store the values for upper 
    // triangle of the pattern 
    for ($k = 0; $k < $n; $k++) 
    { 
        $j = $k; 
        $i = 0; 
        while ($j >= 0)
        { 
            $arr[$i][$j] = $p; 
            $p++; 
            $i = $i + 1; 
            $j = $j - 1; 
        } 
    } 
 
    // Store the values for lower 
    // triangle of the pattern 
    for ($k = 1; $k < $n; $k++) 
    { 
        $i = $k; 
        $j = $n - 1; 
        $f = $k; 
        while ($j >= $f) 
        { 
            $arr[$i][$j] = $p; 
            $p++; 
            $i = $i + 1; 
            $j = $j - 1; 
        } 
    } 
 
    // Print the pattern 
    for ($i = 0; $i < $n; $i++) 
    { 
        for ($j = 0; $j < $n; $j++) 
        { 
            echo($arr[$i][$j] . " "); 
        } 
        echo("\n");
    } 
} 
 
// Driver code 
$n = 3; 
 
printPattern($n); 
 
// This code is contributed 
// by Mukul Singh
?>

Javascript

<script>
    // Javascript program to print the required pattern 
     
    // Function to print the required pattern 
    function printPattern(n) 
    { 
        // arr[][] will store the pattern matrix 
        let arr = new Array(n);
        for(let i = 0; i < n; i++)
        {
            arr[i] = new Array(n);
            for(let j = 0; j < n; j++)
            {
                arr[i][j] = 0;
            }
        }
        let k, i, j, p = 1, f ; 
       
        // Store the values for upper triangle 
        // of the pattern 
        for (k = 0; k < n; k++) { 
            j = k; 
            i = 0; 
            while (j >= 0) { 
                arr[i][j] = p; 
                p++; 
                i = i + 1; 
                j = j - 1; 
            } 
        } 
       
        // Store the values for lower triangle 
        // of the pattern 
        for (k = 1; k < n; k++) { 
            i = k; 
            j = n - 1; 
            f = k; 
            while (j >= f) { 
                arr[i][j] = p; 
                p++; 
                i = i + 1; 
                j = j - 1; 
            } 
        } 
       
        // Print the pattern 
        for (i = 0; i < n; i++) { 
            for (j = 0; j < n; j++) { 
                document.write(arr[i][j] + " ") ; 
            } 
            document.write("<br>") ;
        } 
    } 
     
    let n = 3;       
      printPattern(n); 
 
// This code is contributed by decode2207.
</script>

Output:

1 2 4 
3 5 7 
6 8 9

Time complexity: O(n^2) for given n*n matrix

Auxiliary space: O(n^2) because using space for array arr

Feeling lost in the world of random DSA topics, wasting time without progress? It’s time for a change! Join our DSA course, where we’ll guide you on an exciting journey to master DSA efficiently and on schedule.
Ready to dive in? Explore our Free Demo Content and join our DSA course, trusted by over 100,000 zambiatek!