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Common Elements in the Row’s of Matrix

Program to check the common elements in the Row’s of Matrix

Definition & Explanation

Example:
Input:
Output:

More Description

Program Logic

Desc

C

Method 1 :

#include <stdio.h>

void findCommonElements(int matrix[][3], int rows, int cols) {
    if (rows == 0 || cols == 0)
        return;

    // Convert the first row to a set
    int commonElements[cols];
    for (int j = 0; j < cols; j++)
        commonElements[j] = matrix[0][j];

    // Find the intersection of sets for each subsequent row
    for (int i = 1; i < rows; i++) {
        for (int j = 0; j < cols; j++) {
            if (commonElements[j] != matrix[i][j])
                commonElements[j] = -1;
        }
    }

    // Print the common elements
    printf("Common elements in all rows: ");
    for (int j = 0; j < cols; j++) {
        if (commonElements[j] != -1)
            printf("%d ", commonElements[j]);
    }
    printf("\n");
}

int main() {
    int matrix[3][3] = {
        {1, 2, 3},
        {2, 3, 4},
        {3, 4, 5}
    };
    int rows = 3, cols = 3;

    findCommonElements(matrix, rows, cols);

    return 0;
}

Output :

C++

Method 1 :

#include <iostream>
#include <vector>
#include <unordered_set>

using namespace std;

void findCommonElements(vector<vector<int>>& matrix) {
    if (matrix.empty() || matrix[0].empty())
        return;

    unordered_set<int> commonElements(matrix[0].begin(), matrix[0].end());

    // Find the intersection of sets for each subsequent row
    for (int i = 1; i < matrix.size(); i++) {
        unordered_set<int> rowSet(matrix[i].begin(), matrix[i].end());
        for (auto it = commonElements.begin(); it != commonElements.end();) {
            if (rowSet.find(*it) == rowSet.end())
                it = commonElements.erase(it);
            else
                ++it;
        }
    }

    // Print the common elements
    cout << "Common elements in all rows: ";
    for (int num : commonElements)
        cout << num << " ";
    cout << endl;
}

int main() {
    vector<vector<int>> matrix = {
        {1, 2, 3},
        {2, 3, 4},
        {3, 4, 5}
    };

    findCommonElements(matrix);

    return 0;
}

Output :

JAVA

Method 1 :

import java.util.HashSet;
import java.util.Set;

public class Main {
    public static void findCommonElements(int[][] matrix) {
        if (matrix.length == 0 || matrix[0].length == 0)
            return;

        Set<Integer> commonElements = new HashSet<>();
        for (int num : matrix[0])
            commonElements.add(num);

        // Find the intersection of sets for each subsequent row
        for (int i = 1; i < matrix.length; i++) {
            Set<Integer> rowSet = new HashSet<>();
            for (int num : matrix[i])
                rowSet.add(num);

            commonElements.retainAll(rowSet);
        }

        // Print the common elements
        System.out.print("Common elements in all rows: ");
        for (int num : commonElements)
            System.out.print(num + " ");
        System.out.println();
    }

    public static void main(String[] args) {
        int[][] matrix = {
            {1, 2, 3},
            {2, 3, 4},
            {3, 4, 5}
        };

        findCommonElements(matrix);
    }
}

Output :

Python

Method 1 :

def common_elements(matrix):
    if not matrix:
        return []

    # Convert the first row to a set
    common_elements_set = set(matrix[0])

    # Find the intersection of sets for each subsequent row
    for row in matrix[1:]:
        common_elements_set.intersection_update(row)

    return list(common_elements_set)

# Example usage:
matrix = [
    [1, 2, 3],
    [2, 3, 4],
    [3, 4, 5]
]
result = common_elements(matrix)
print("Common elements in all rows:", result)  # Output: [3]

Output :

Common elements in all rows: [3]
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