# Program to find smallest intersecting element of each row in a matrix in Python

PythonServer Side ProgrammingProgramming

Suppose we have a 2D matrix where each row is sorted in ascending order. We have to find the smallest number that exists in every row. If there's no such result, then return −1.

So, if the input is like

 2 3 5 5 10 10 1 3 5

then the output will be 5

To solve this, we will follow these steps −

• if matrix is empty, then

• return −1

• first := a new set from first row of matrix

• for each row in matrix, do

• first := Intersect first a set of elements of row

• if first is empty, then

• return −1

• return minimum of first

Let us see the following implementation to get better understanding −

## Example

Live Demo

class Solution:
def solve(self, matrix):
if not matrix:
return -1
first = set(matrix[0])
for row in matrix:
first &= set(row)
if not first:
return -1
return min(first)
ob1 = Solution()
matrix = [
[2, 3, 5],
[5, 10, 10],
[1, 3, 5]
]
print(ob1.solve(matrix))

## Input

matrix = [
[2, 3, 5],
[5, 10, 10],
[1, 3, 5] ]

## Output

5
Published on 21-Oct-2020 11:05:35