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
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:
14
Time Complexity : O(N x M)
Auxiliary Space : O(N x M)
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