Common elements in all rows of a given matrix in Python

May 4, 2022

Common elements in all rows of a given matrix in Python

Here, on this page, we will discuss the program to find the Common elements in all rows of a given matrix in Python Programming language.

Algorithm ( Method 1 )

In this algorithm, we will check for every element in the first row, if that is present in other rows or not.

For checking the presence, take one variable count.
Now, run a loop from index 1 to M.
Take a variable flag =0;
Now, run a loop from index 0 to N, if (x==mat[i][j]) set flag =1 and break the loop.
After coming out from loop check if(flag==1) set, count++.
At last, check if count == M-1, print that value.

Time and Space Complexity :

Time complexity: O(M*M*N)
Space complexity: O(1)

Python Code

Run

def find(mat, N, M):
    for j in range(0, N):
        x, count = mat[0][j], 0

        for i in range(1, M):
            flag = 0
            for k in range(0, N):
                if x == mat[i][k]:
                    flag = 1
                    mat[i][k] = -1
                    break
            if flag == 1:
                count += 1
        if count == M - 1:
            print(x)


N, M = 4, 4
mat = [[10, 20, 30, 40],
       [15, 25, 35, 30],
       [27, 30, 37, 48],
       [32, 33, 39, 30]]
find(mat, N, M)

Output

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