Given a NxM matrix of integers containing duplicate elements. The task is to find the sum of all even occurring elements in the given matrix. That is the sum of all such elements whose frequency is even in the matrix.
Examples:
Input : mat[] = {{1, 1, 2}, {2, 3, 3}, {4, 5, 3}} Output : 18 The even occurring elements are 1, 2 and their number of occurrences are 2, 2 respectively. Therefore, sum = 1+1+2+2 = 6. Input : mat[] = {{10, 20}, {40, 40}} Output : 80
Approach:
- Traverse the matrix and use a map 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 even, 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 even // 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 even // frequency elements in a Matrix int sumOddOccurring( int arr[N][M]) { // Store frequency of elements // in matrix unordered_map< int , int > mp; for ( int i = 0; i < N; i++) { for ( int j = 0; j < M; j++) { mp[arr[i][j]]++; } } // Sum even frequency elements int sum = 0; for ( auto itr = mp.begin(); itr != mp.end(); itr++) { if (itr->second % 2 == 0) { int x = itr->second; 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 even // frequency elements in a Matrix import java.util.*; class GFG { static final int N = 3 ; // Rows static final int M = 3 ; // Columns // Function to find sum of all even // frequency elements in a Matrix static int sumOddOccurring( int arr[][]) { // Store frequency of elements // in matrix Map<Integer, Integer> mp = new HashMap<Integer, Integer>(); for ( int i = 0 ; i < N; i++) { for ( int j = 0 ; j < M; j++) { if (mp.get(arr[i][j]) == null ) mp.put(arr[i][j], 1 ); else mp.put(arr[i][j], (mp.get(arr[i][j]) + 1 )); } } // Sum even frequency elements int sum = 0 ; Set< Map.Entry<Integer, Integer> > st = mp.entrySet(); for (Map.Entry< Integer, Integer> me:st) { if (me.getValue() % 2 == 0 ) { int x = me.getValue(); sum += (me.getKey()) * (me.getValue()); } } return sum; } // Driver Code public static void main(String args[]) { int mat[][] = {{ 1 , 2 , 3 }, { 1 , 3 , 2 }, { 1 , 5 , 6 }}; System.out.print(sumOddOccurring(mat)); } } // This code is contributed by Arnab Kundu |
Python3
# Python3 program to find sum of all even # frequency elements in a Matrix import sys N = 3 # Rows M = 3 # Columns # Function to find sum of all even # frequency elements in a Matrix def sumOddOccurring(arr): # Store frequencies of elements # in matrix mp = dict () for i in range (N): for j in range (M): if arr[i][j] in mp: mp[arr[i][j]] + = 1 else : mp[arr[i][j]] = 1 # Sum of even frequency elements s = 0 for i in mp: if mp[i] % 2 = = 0 : x = mp[i] s + = i * mp[i] return s # Driver code if __name__ = = "__main__" : mat = [[ 1 , 2 , 3 ], [ 1 , 3 , 2 ], [ 1 , 5 , 6 ]] print (sumOddOccurring(mat)) # This code is contributed by # sanjeev2552 |
C#
// C# program to find sum of all even // frequency elements in a Matrix using System; using System.Collections.Generic; class Sol { static readonly int N = 3; // Rows static readonly int M = 3; // Columns // Function to find sum of all even // frequency elements in a Matrix static int sumOddOccurring( int [,]arr) { // Store frequency 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])) mp.Add(arr[i, j], 1); else { var val = mp[arr[i, j]]; mp.Remove(arr[i, j]); mp.Add(arr[i, j], val + 1); } } } // Sum even frequency elements int sum = 0; foreach (KeyValuePair< int , int > entry in mp) { if (entry.Value % 2 == 0){ sum += entry.Key * entry.Value; } } return sum; } // Driver Code public static void Main(String []args) { int [,]mat = { { 1, 2, 3 }, { 1, 3, 2 }, { 1, 5, 6 } }; Console.Write( sumOddOccurring(mat) ); } } /* This code contributed by PrinciRaj1992 */ |
Javascript
<script> // JavaScript program to find sum of all even // frequency elements in a Matrix var N = 3; // Rows var M = 3; // Columns // Function to find sum of all even // frequency elements in a Matrix function sumOddOccurring(arr) { // Store frequency of elements // in matrix var mp = new Map(); for ( var i = 0; i < N; i++) { for ( var j = 0; j < M; j++) { if (!mp.has(arr[i][j])) mp.set(arr[i][j], 1); else { var val = mp.get(arr[i][j]); mp. delete (arr[i][j]); mp.set(arr[i][j], val + 1); } } } // Sum even frequency elements var sum = 0; mp.forEach((value, key) => { if (value % 2 == 0){ sum += key * value; } }); return sum; } // Driver Code var mat = [[1, 2, 3 ], [1, 3, 2 ], [1, 5, 6 ]]; document.write( sumOddOccurring(mat) ); </script> |
10
Complexity Analysis:
- Time Complexity: O(N x M)
- Auxiliary Complexity: O(N x M)
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