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

Python Server Side Programming Programming

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

Arnab Chakraborty

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

Previous Page Print Page