# Sum of all odd frequency elements in a Matrix

Given a NxM matrix of integers containing duplicate elements. The task is to find the sum of all odd occurring elements in the given matrix. That is the sum of all such elements whose frequency is odd in the matrix.

Examples:

```Input : mat[] = {{1, 1, 2},
{2, 3, 3},
{4, 5, 3}}
Output : 18
The odd occurring elements are 3, 4, 5 and their number
of occurrences are 3, 1, 1 respectively. Therefore,
sum = 3+3+3+4+5 = 18.

Input : mat[] = {{10, 20},
{40, 40}}
Output : 30
```

## Recommended: Please try your approach on {IDE} first, before moving on to the solution.

Approach:

• Traverse the matrix and use a map in C++ to store the frequency of elements of the matrix such that the key of map is the matrix element and value is its frequency in the matrix.
• Then, traverse the map to find the frequency of elements and check if it is odd, if it is odd, then add this element it’s frequency times to sum.

Below is the implementation of the above approach:

## C++

 `// C++ program to find sum of all odd ` `// frequency elements in a Matrix ` ` `  `#include ` `using` `namespace` `std; ` ` `  `#define N 3 // Rows ` `#define M 3 // Columns ` ` `  `// Function to find sum of all odd ` `// frequency elements in a Matrix ` `int` `sumOddOccurring(``int` `arr[N][M]) ` `{ ` ` `  `    ``// Store frequencies of elements ` `    ``// in matrix ` `    ``map<``int``, ``int``> mp; ` `    ``for` `(``int` `i = 0; i < N; i++) { ` `        ``for` `(``int` `j = 0; j < M; j++) { ` `            ``mp[arr[i][j]]++; ` `        ``} ` `    ``} ` ` `  `    ``// Sum of odd frequency elements ` `    ``int` `sum = 0; ` `    ``for` `(``auto` `itr = mp.begin(); itr != mp.end(); itr++) { ` `        ``if` `(itr->second % 2 != 0) { ` `            ``sum += (itr->first) * (itr->second); ` `        ``} ` `    ``} ` ` `  `    ``return` `sum; ` `} ` ` `  `// Driver Code ` `int` `main() ` `{ ` ` `  `    ``int` `mat[N][M] = { { 1, 2, 3 }, ` `                      ``{ 1, 3, 2 }, ` `                      ``{ 1, 5, 6 } }; ` ` `  `    ``cout << sumOddOccurring(mat) << endl; ` ` `  `    ``return` `0; ` `} `

## Java

 `// Java program to find sum of all odd  ` `// frequency elements in a Matrix  ` ` `  `import` `java.util.*; ` ` `  `class` `GFG  ` `{ ` ` `  `    ``static` `int` `N = ``3``; ``// Rows  ` `    ``static` `int` `M = ``3``; ``// Columns  ` ` `  `    ``// Function to find sum of all odd  ` `    ``// frequency elements in a Matrix  ` `    ``static` `int` `sumOddOccurring(``int` `arr[][])  ` `    ``{ ` `        ``// Store frequencies of elements  ` `        ``// in matrix  ` `        ``Map mp = ``new` `HashMap<>(); ` `        ``for` `(``int` `i = ``0``; i < N; i++)  ` `        ``{ ` `            ``for` `(``int` `j = ``0``; j < M; j++)  ` `            ``{ ` `                ``if` `(mp.containsKey(arr[i][j]))  ` `                ``{ ` `                    ``mp.put(arr[i][j], mp.get(arr[i][j]) + ``1``); ` `                ``} ` `                ``else` `                ``{ ` `                    ``mp.put(arr[i][j], ``1``); ` `                ``} ` `            ``} ` `        ``} ` ` `  `        ``int` `sum = ``0``; ` `         `  `        ``// Sum of odd frequency elements ` `        ``for` `(Map.Entry itr : mp.entrySet()) ` `        ``{ ` `            ``if` `(itr.getValue() % ``2` `!= ``0``) ` `            ``{ ` `                ``sum += (itr.getKey()) * (itr.getValue()); ` `            ``} ` `        ``} ` ` `  `        ``return` `sum; ` `    ``} ` ` `  `    ``// Driver Code  ` `    ``public` `static` `void` `main(String[] args)  ` `    ``{ ` `        ``int` `mat[][] = {{``1``, ``2``, ``3``}, ` `        ``{``1``, ``3``, ``2``}, ` `        ``{``1``, ``5``, ``6``}}; ` ` `  `        ``System.out.println(sumOddOccurring(mat)); ` `    ``} ` `} ` ` `  `// This code is contributed by 29AjayKumar `

## Python3

 `# Python3 program to find sum of all odd  ` `# frequency elements in a Matrix  ` ` `  `# Function to find sum of all odd  ` `# frequency elements in a Matrix  ` `def` `sumOddOccurring(mat): ` `     `  `    ``# Store frequencies of elements  ` `    ``# in matrix ` `    ``mp ``=` `{} ` `    ``n, m ``=` `len``(mat), ``len``(mat[``0``]) ` `    ``for` `i ``in` `range``(n): ` `        ``for` `j ``in` `range``(m): ` `            ``if` `mat[i][j] ``in` `mp: ` `                ``mp[mat[i][j]] ``=` `mp.get(mat[i][j]) ``+` `1` `            ``else``: ` `                ``mp[mat[i][j]] ``=` `1` ` `  `    ``# Sum of odd frequency elements  ` `    ``_sum ``=` `0` `    ``for` `i ``in` `range``(n): ` `        ``for` `j ``in` `range``(m): ` `            ``if` `mp.get(mat[i][j]) ``%` `2` `=``=` `1``: ` `                ``_sum``+``=``mat[i][j] ` `    ``return` `_sum ` ` `  `# Driver Code  ` `if` `__name__``=``=``'__main__'``: ` `    ``mat``=``[[``1``,``2``,``3``],[``1``,``3``,``2``],[``1``,``5``,``6``]] ` `    ``print``(sumOddOccurring(mat)) ` ` `  `# This code is Contributed by Vikash Kumar 37 `

## C#

 `// C# program to find sum of all odd  ` `// frequency elements in a Matrix  ` `using` `System; ` `using` `System.Collections.Generic;  ` ` `  `class` `GFG  ` `{ ` ` `  `    ``static` `int` `N = 3; ``// Rows  ` `    ``static` `int` `M = 3; ``// Columns  ` ` `  `    ``// Function to find sum of all odd  ` `    ``// frequency elements in a Matrix  ` `    ``static` `int` `sumOddOccurring(``int` `[,]arr)  ` `    ``{ ` `        ``// Store frequencies of elements  ` `        ``// in matrix  ` `        ``Dictionary<``int``,``int``> mp = ``new` `Dictionary<``int``,``int``>(); ` `        ``for` `(``int` `i = 0; i < N; i++)  ` `        ``{ ` `            ``for` `(``int` `j = 0; j < M; j++)  ` `            ``{ ` `                ``if` `(mp.ContainsKey(arr[i,j]))  ` `                ``{ ` `                    ``var` `v = mp[arr[i,j]]; ` `                    ``mp.Remove(arr[i,j]); ` `                    ``mp.Add(arr[i,j], ++v); ` `                ``} ` `                ``else` `                ``{ ` `                    ``mp.Add(arr[i,j], 1); ` `                ``} ` `            ``} ` `        ``} ` ` `  `        ``int` `sum = 0; ` `         `  `        ``// Sum of odd frequency elements ` `        ``foreach``(KeyValuePair<``int``, ``int``> itr ``in` `mp) ` `        ``{ ` `            ``if` `(itr.Value % 2 != 0) ` `            ``{ ` `                ``sum += (itr.Key) * (itr.Value); ` `            ``} ` `        ``} ` ` `  `        ``return` `sum; ` `    ``} ` ` `  `    ``// Driver Code  ` `    ``public` `static` `void` `Main(String[] args)  ` `    ``{ ` `        ``int` `[,]mat = {{1, 2, 3}, ` `        ``{1, 3, 2}, ` `        ``{1, 5, 6}}; ` ` `  `        ``Console.WriteLine(sumOddOccurring(mat)); ` `    ``} ` `} ` ` `  `// This code is contributed by Princi Singh `

Output:

```14
```

Time Complexity : O(N x M)
Auxiliary Space : O(N x M)

My Personal Notes arrow_drop_up

Check out this Author's contributed articles.

If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

Please Improve this article if you find anything incorrect by clicking on the "Improve Article" button below.

Article Tags :
Practice Tags :

Be the First to upvote.

Please write to us at contribute@geeksforgeeks.org to report any issue with the above content.