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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2 comments on “Common elements in all rows of a given matrix in Python”

varikutisrinivas123
def sort(arr):
l=[]
for i in range(len(arr)):
k=arr[0][i]
for j in range(1,len(arr)):
if k in arr[j]:
continue
else:
break
else:
l.append(k)
print(l)

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

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harryharish231
r=int(input())
c=int(input())
matrix=[]
sort_mat=[]
# taking inputs in matrix
for _ in range(r):
row=[]
for _ in range(c):
row.append(int(input()))
matrix.append(row)
# print(matrix)
# changing matrix into a single array (flatten)
for i in range(r):
for j in range(c):
sort_mat.append(matrix[i][j])
# print(sort_mat)
# count the maximum times a number is repeated
max_count=0
for i in sort_mat:
count=sort_mat.count(i)
if count>max_count:
max_count=count
store=i
print(i,max_count)

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