Find maximum element of each row in a matrix

Given a matrix, the task is to find the maximum element of each row.

Examples:

Input :  [1, 2, 3]
         [1, 4, 9]
         [76, 34, 21]

Output :
3
9
76

Input : [1, 2, 3, 21]
        [12, 1, 65, 9]
        [1, 56, 34, 2]
Output :
21
65
56

Approach : Approach is very simple. The idea is to run the loop for no_of_rows. Check each element inside the row and find for the maximum element. Finally, print the element. 

Implementation:

C++

#include<bits/stdc++.h>
using namespace std;

const int N = 4;

void printArray(int result[], int no_of_rows) {
    for (int i = 0; i < no_of_rows; i++) {
        cout<< result[i]<<"\n";
    }
}

void maxelement(int no_of_rows, int arr[][N]) {
    int result[no_of_rows];
    for (int i = 0; i < no_of_rows; i++) {
        int max = *max_element(arr[i], arr[i]+N);
        result[i] = max;
    }
    printArray(result,no_of_rows);
}

int main() {
    int arr[][N] = { {3, 4, 1, 8},
                    {1, 4, 9, 11},
                    {76, 34, 21, 1},
                    {2, 1, 4, 5} };
    maxelement(4, arr);
    return 0;
}

Java

// Java program to find maximum
// element of each row in a matrix
public class GFG{

    // Function to get max element
    public static void maxelement(int no_of_rows, int[][] arr) {
        int i = 0;

        // Initialize max to 0 at beginning
        // of finding max element of each row
        int max = 0;
        int[] result = new int[no_of_rows];
        while (i < no_of_rows) {
            for (int j = 0; j < arr[i].length; j++) {
                if (arr[i][j] > max) {
                    max = arr[i][j];
                }
            }
            result[i] = max;
            max =0;
            i++;

        }
        printArray(result);

    }

    // Print array element
    private static void printArray(int[] result) {
        for (int i =0; i<result.length;i++) {
            System.out.println(result[i]);
        }

    }

    // Driver code
    public static void main(String[] args) {
        int[][] arr = new int[][] { {3, 4, 1, 8},
                                    {1, 4, 9, 11},
                                    {76, 34, 21, 1},
                                   {2, 1, 4, 5} };
       // Calling the function
        maxelement(4, arr);
    }
}

Python

# Python program to find maximum
# element of each row in a matrix

# importing numpy
import numpy

# Function to get max element
def maxelement(arr):

    # get number of rows and columns
    no_of_rows = len(arr)
    no_of_column = len(arr[0])

    for i in range(no_of_rows):

        # Initialize max1 to 0 at beginning
        # of finding max element of each row
        max1 = 0
        for j in range(no_of_column):
            if arr[i][j] > max1 :
                max1 = arr[i][j]

        # print maximum element of each row
        print(max1)

# Driver Code
arr = [[3, 4, 1, 8],
       [1, 4, 9, 11],
       [76, 34, 21, 1],
       [2, 1, 4, 5]]

# Calling the function
maxelement(arr)

C#

// C# program to find maximum
// element of each row in a matrix
using System;

class GFG
{

// Function to get max element
public static void maxelement(int no_of_rows,
                              int[][] arr)
{
    int i = 0;

    // Initialize max to 0 at beginning
    // of finding max element of each row
    int max = 0;
    int[] result = new int[no_of_rows];
    while (i < no_of_rows)
    {
        for (int j = 0;
                 j < arr[i].Length; j++)
        {
            if (arr[i][j] > max)
            {
                max = arr[i][j];
            }
        }
        result[i] = max;
        max = 0;
        i++;

    }
    printArray(result);

}

// Print array element
private static void printArray(int[] result)
{
    for (int i = 0; i < result.Length;i++)
    {
        Console.WriteLine(result[i]);
    }

}

// Driver code
public static void Main(string[] args)
{
    int[][] arr = new int[][]
    {
        new int[] {3, 4, 1, 8},
        new int[] {1, 4, 9, 11},
        new int[] {76, 34, 21, 1},
        new int[] {2, 1, 4, 5}
    };

    // Calling the function
    maxelement(4, arr);
}
}

// This code is contributed by Shrikant13

PHP

<?php
// PHP program to find maximum
// element of each row in a matrix
$N = 4;


// Print array element
function printArray($result, $no_of_rows)
{
    for ($i = 0; $i < $no_of_rows; $i++)
    {
        echo $result[$i]."\n";
    }

}

// Function to get max element
function maxelement($no_of_rows, $arr)
{
    global $N;
    $i = 0;

    // Initialize max to 0 at beginning
    // of finding max element of each row
    $max = 0;
    $result=array_fill(0,$no_of_rows,0);
    while ($i < $no_of_rows)
    {
        for ($j = 0; $j < $N; $j++)
        {
            if ($arr[$i][$j] > $max)
            {
                $max = $arr[$i][$j];
            }
        }
        $result[$i] = $max;
        $max = 0;
        $i++;

    }
    printArray($result,$no_of_rows);

}

// Driver code
$arr = array(array(3, 4, 1, 8),
                array(1, 4, 9, 11),
                array(76, 34, 21, 1),
                array(2, 1, 4, 5));
// Calling the function
maxelement(4, $arr);

// This code is contributed by mits
?>

Javascript

<script>
// javascript program to find maximum
// element of each row in a matrix
// Function to get max element
function maxelement(no_of_rows, arr)
{
    var i = 0;

    // Initialize max to 0 at beginning
    // of finding max element of each row
    var max = 0;
    var result = Array.from({length: no_of_rows}, (_, i) => 0);
    while (i < no_of_rows)
    {
        for (var j = 0; j < arr[i].length; j++)
        {
            if (arr[i][j] > max)
            {
                max = arr[i][j];
            }
        }
        result[i] = max;
        max = 0;
        i++;

    }
    printArray(result);

}

// Print array element
function printArray(result)
{
    for (var i = 0; i < result.length; i++)
    {
        document.write(result[i]+"<br>");
    }

}

// Driver code
    var arr = [[3, 4, 1, 8],
    [ 1, 4, 9, 11],
    [ 76, 34, 21, 1],
   [ 2, 1, 4, 5] ];

// Calling the function
maxelement(4, arr);

// This code is contributed by 29AjayKumar
</script>

Output

8
11
76
5

Complexity Analysis:

• Time Complexity: O(n*m) (where, n refers to no. of rows and m refers to no. of columns)
• Auxiliary Space: O(n) (where, n refers to no. of rows)

METHOD: Using List Comprehension.

APPROACH:

It is a concise way of creating a list in Python. We iterate through each row in the matrix using list comprehension and find the maximum element in the current row using the max() function. We then append the maximum element to a new list called “output”. Finally, we print the “output” list which contains the maximum element of each row in the matrix.

ALGORITHM:

1. Iterate through each row of the matrix.
2. Find the maximum element in the current row using the max() function.
3. Append the maximum element to the output list.
4. Return the output list.

Python3

matrix = [[1, 2, 3], [1, 4, 9], [76, 34, 21]]
output = [max(row) for row in matrix]
print(output)

Output

[3, 9, 76]

Time complexity: O(nm) where n is the number of rows and m is the number of columns in the matrix.
Auxiliary Space: O(n) where n is the number of rows in the matrix