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 <bits/stdc++.h> 
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<Integer, Integer> 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<Integer, Integer> 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:

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

My Personal Notes

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

C++

Java

Python3

C#

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