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# Sum of columns of a 2-D Matrix where first element is odd

• Last Updated : 21 May, 2021

Given a matrix mat[][], the task is to print the sum of the columns where the first element is odd.

Examples:

Input: mat[][] = {
{8, 2, 3, 5},
{9, 8, 7, 6},
{1, 2, 5, 5} }
Output: 31
Only the third and the fourth columns start with an odd element.
And, sum = 3 + 7 + 5 + 5 + 6 + 5 = 31

Input: mat[][] = {
{10, 80, 20, 12, 40},
{10, 21, 23, 45, 29},
{19, 18, 17, 16, 15},
{10, 11, 12, 13, 14} }
Output: -1

Approach: Initialize sum = 0 and start traversing the first row. If any element in the first row is odd, then add all the elements of that column to the sum. Print the sum at the end.

Below is the implementation of the above approach:

## C++

 `// CPP implementation of the approach``#include``using` `namespace` `std;` `// Function to return the sum of those columns``// of a given matrix that start with an odd element``int` `sumColumns(``int` `arr[], ``int` `r, ``int` `c)``{``    ` `    ``// Initialize sum to 0``    ``int` `sum = 0;``    ` `    ``// Traverse through all the elements of the first row``    ``for` `(``int` `j = 0; j < c; j++)``    ``{``        ``// If the element is odd``        ``if` `(arr[j] % 2 != 0)``        ``{``            ``// Add all the elements of that column``            ``for` `(``int` `i = 0; i < r; i++)``                ``sum += arr[i][j];``        ``}``            ` `            ` `    ``}` `    ``// Return the sum``    ``return` `sum;` `}``    ` `// Driver code``int` `main()``{``int` `arr = {{8, 2, 3, 5},{9, 8, 7, 6}, {1, 2, 5, 5}};``int` `r = ``sizeof``(arr)/``sizeof``(arr);``int` `c = ``sizeof``(arr)/``sizeof``(``int``);``cout<<(sumColumns(arr, 3, 4));``}` `// This code is contributed by``// Surendra_Gangwar`

## Java

 `// Java implementation of the approach``import` `java.io.*;` `class` `GFG``{``    ` `// Function to return the sum of those columns``// of a given matrix that start with an odd element``static` `int` `sumColumns(``int` `arr[][], ``int` `r, ``int` `c)``{``    ` `    ``// Initialize sum to 0``    ``int` `sum = ``0``;``    ` `    ``// Traverse through all the``    ``// elements of the first row``    ``for` `(``int` `j = ``0``; j < c; j++)``    ``{``        ``// If the element is odd``        ``if` `(arr[``0``][j] % ``2` `!= ``0``)``        ``{``            ``// Add all the elements of that column``            ``for` `(``int` `i = ``0``; i < r; i++)``                ``sum += arr[i][j];``        ``}``    ``}` `    ``// Return the sum``    ``return` `sum;``}``    ` `// Driver code``public` `static` `void` `main (String[] args)``{``    ``int` `arr[][] = {{``8``, ``2``, ``3``, ``5``},{``9``, ``8``, ``7``, ``6``}, {``1``, ``2``, ``5``, ``5``}};``    ``System.out.println(sumColumns(arr, ``3``, ``4``));``}``}` `// This code is contributed by``// shs..`

## Python3

 `# Python3 implementation of the approach` `# Function to return the sum of those columns``# of a given matrix that start with an odd element``def` `sumColumns(arr, r, c):``    ` `    ``# Initialize sum to 0``    ``sum` `=` `0``    ` `    ``# Traverse through all the elements of the first row``    ``for` `j ``in` `range``(c):``        ` `        ``# If the element is odd``        ``if` `(arr[``0``][j] ``%` `2` `!``=` `0``):``            ` `            ``# Add all the elements of that column``            ``for` `i ``in` `range``(r):``                ``sum` `+``=` `arr[i][j]` `    ``# Return the sum``    ``return` `sum` `# Driver code``arr ``=` `[ [``8``, ``2``, ``3``, ``5``], [``9``, ``8``, ``7``, ``6``], [``1``, ``2``, ``5``, ``5``] ]``r ``=` `len``(arr)``c ``=` `len``(arr[``0``])``print``(sumColumns(arr, r, c))`

## C#

 `// C# implementation of the approach``using` `System;` `class` `GFG``{``    ` `    ``// Function to return the sum of those columns``    ``// of a given matrix that start with an odd element``    ``static` `int` `sumColumns(``int` `[,]arr, ``int` `r, ``int` `c)``    ``{``        ` `        ``// Initialize sum to 0``        ``int` `sum = 0;``        ` `        ``// Traverse through all the``        ``// elements of the first row``        ``for` `(``int` `j = 0; j < c; j++)``        ``{``            ``// If the element is odd``            ``if` `(arr[0, j] % 2 != 0)``            ``{``                ``// Add all the elements of that column``                ``for` `(``int` `i = 0; i < r; i++)``                    ``sum += arr[i, j];``            ``}``        ``}``    ` `        ``// Return the sum``        ``return` `sum;``    ``}``        ` `    ``// Driver code``    ``public` `static` `void` `Main()``    ``{``        ``int` `[,]arr= {{8, 2, 3, 5}, {9, 8, 7, 6}, {1, 2, 5, 5}};``        ``Console.WriteLine(sumColumns(arr, 3, 4));``    ``}``}` `// This code is contributed by aishwarya.27`

## PHP

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## Javascript

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Output:
`31`

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