Find unique elements in a matrix

Given a matrix mat[][] having n rows and m columns. We need to find unique elements in matrix i.e, those elements which are not repeated in the matrix or those elements whose frequency is 1.

Examples:

Input :  20  15  30  2
         2   3   5   30
         6   7   6   8
Output : 3  20  5  7  8  15 

Input :  1  2  3  
         5  6  2
         1  3  5
         6  2  2
Output : No unique element in the matrix

Follow these steps to find unique element:
1. Create an empty hash table or dictionary.
2. Traverse through all the elements of the matrix
3. If element is present in the dictionary, then increment its count
4. Otherwise insert element with value = 1.



C++

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// C++ program to find unique
// element in matrix
#include<bits/stdc++.h>
using namespace std;
#define R 4
#define C 4
  
// function that calculate unique element
int unique(int mat[R][C], int n, int m)
{
    int maximum = 0, flag = 0;
    for(int i = 0; i < n; i++) 
        for(int j = 0; j < m; j++)
            // Find maximum element in
            // a matrix
            if(maximum < mat[i][j])
                    maximum = mat[i][j];
  
    // Take 1-D array of (maximum + 1)
    // size
    int b[maximum + 1] = {0};
    for(int i = 0 ; i < n; i++)
        for(int j = 0; j < m; j++)
            b[mat[i][j]]++;
  
    //print unique element
    for(int i = 1; i <= maximum; i++)
        if(b[i] == 1)
            cout << i << " ";
            flag = 1;
              
    if(!flag){
        cout << "No unique element in the matrix";
    }
}
  
// Driver program
int main()
{
    int mat[R][C] = {{ 1, 2, 3, 20},
                     {5, 6, 20, 25},
                     {1, 3, 5, 6},
                     {6, 7, 8, 15}};
                       
    // function that calculate unique element
    unique(mat, R, C);
    return 0;
}
  
// This code is contributed by Naman_Garg.

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Java














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// Java program to find unique 


// element in matrix 


class GFG 


{ 


static int R = 4, C = 4; 


  


// function that calculate  


// unique element 


static void unique(int mat[][],  


                   int n, int m) 


{ 


    int maximum = 0, flag = 0; 


    for(int i = 0; i < n; i++)  


        for(int j = 0; j < m; j++) 


          


            // Find maximum element  


            // in a matrix 


            if(maximum < mat[i][j]) 


                    maximum = mat[i][j]; 


  


    // Take 1-D array of  


    // (maximum + 1) size 


    int b[] = new int [maximum + 1]; 


    for(int i = 0 ; i < n; i++) 


        for(int j = 0; j < m; j++) 


            b[mat[i][j]]++; 


  


    //print unique element 


    for(int i = 1; i <= maximum; i++) 


        if(b[i] == 1) 


            System.out.print(i + " "); 


            flag = 1; 


              


    if(flag == 0) 


    { 


        System.out.println("No unique element " +  


                                "in the matrix"); 


    } 


} 


  


// Driver Code 


public static void main(String args[]) 


{ 


    int mat[][] = {{1, 2, 3, 20}, 


                   {5, 6, 20, 25}, 


                   {1, 3, 5, 6}, 


                   {6, 7, 8, 15}}; 


                      


    // function that calculate  


    // unique element 


    unique(mat, R, C); 


} 


} 


  


// This code is contributed 


// by Arnab Kundu 



















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Python3














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# Python 3 program to find unique 


# element in matrix 


def unique(mat, n, m): 


  


    maximum = 0; flag = 0


      


    for i in range(0, n): 


        for j in range(0, m): 


              


            # Find maximum element in 


            # a matrix 


            if(maximum < mat[i][j]): 


                maximum = mat[i][j]; 


  


    uniqueElementDict = [0] * (maximum + 1) 


  


    # loops to traverse through the matrix  


    for i in range(0, n): 


        for j in range(0, m): 


                uniqueElementDict[mat[i][j]] += 1


  


    # Print all those keys whose count is 1 


    for key in range(maximum + 1): 


        if uniqueElementDict[key] == 1: 


            print (key, end = " ") 


            flag = 1


      


    if(flag == 0): 


        print("No unique element in the matrix") 


  


# Driver Code 


mat = [[1, 2, 3, 20],  


       [5, 6, 20, 25], 


       [1, 3, 5, 6], 


       [6, 7, 8, 15]] 


n = 4


m = 4


unique(mat, n, m) 



















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C#














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// C# program to find unique  


// element in matrix 


using System; 


  


class GFG  


{  


static int R = 4, C = 4;  


  


// function that calculate  


// unique element  


static void unique(int [,]mat,  


                   int n, int m)  


{  


    int maximum = 0, flag = 0;  


    for(int i = 0; i < n; i++)  


        for(int j = 0; j < m; j++)  


          


            // Find maximum element  


            // in a matrix  


            if(maximum < mat[i, j])  


                    maximum = mat[i, j];  


  


    // Take 1-D array of  


    // (maximum + 1) size  


    int []b = new int [maximum + 1];  


    for(int i = 0 ; i < n; i++)  


        for(int j = 0; j < m; j++)  


            b[mat[i, j]]++;  


  


    // print unique element  


    for(int i = 1; i <= maximum; i++)  


        if(b[i] == 1)  


            Console.Write(i + " ");  


            flag = 1;  


              


    if(flag == 0)  


    {  


        Console.WriteLine("No unique element " +  


                               "in the matrix");  


    }  


}  


  


// Driver Code  


public static void Main()  


{  


    int [,]mat = {{1, 2, 3, 20},  


                  {5, 6, 20, 25},  


                  {1, 3, 5, 6},  


                  {6, 7, 8, 15}};  


                      


    // function that calculate  


    // unique element  


    unique(mat, R, C);  


}  


}  


  


// This code is contributed  


// by Subhadeep 



















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PHP














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<?php 


// PHP program to find unique 


// element in matrix 


  


$R = 4; 


$C = 4; 


  


// function that calculate unique element 


function unique($mat, $n, $m) 


{ 


    $maximum = 0; 


    $flag = 0; 


    for($i = 0; $i < $n; $i++)  


        for($j = 0; $j < $m; $j++) 


          


            // Find maximum element in 


            // a matrix 


            if($maximum < $mat[$i][$j]) 


                    $maximum = $mat[$i][$j]; 


  


    // Take 1-D array of (maximum + 1) 


    // size 


    $b = array(); 


    for($j = 0; $j < $maximum + 1; $j++) 


        $b[$j] = 0; 


      


    for($i = 0 ; $i < $n; $i++) 


        for($j = 0; $j < $m; $j++) 


            $b[$mat[$i][$j]]++; 


  


    // print unique element 


    for($i = 1; $i <= $maximum; $i++) 


        if($b[$i] == 1) 


            echo "$i "; 


            $flag = 1; 


              


    if(!$flag) 


    { 


        echo "No unique element in the matrix"; 


    } 


} 


  


// Driver Code 


$mat = array(array(1, 2, 3, 20), 


             array(5, 6, 20, 25), 


             array(1, 3, 5, 6), 


             array(6, 7, 8, 15)); 


                  


// function that calculate unique element 


unique($mat, $R, $C); 


  


// This code is contributed by iAyushRaj 


?> 



















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Output:


2 7 8 25 15 




          
          
          

          

    

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    Article Tags : 
Matrix

           	
Practice Tags : 
python-dict
Matrix

        

         

         
 
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