[Coding Challenge] Special Elements in Matrix

This coding challenge was asked in Goldman Sachs coding round.

Problem Statement:

Given a matrix of size m*n, m denotes the row starting with index 0 and n denotes the column starting with index 0.

The matrix will hold distinct integers as elements.

We need to find the distinct number of positional elements which are either the minimum or maximum in their corresponding row or column.

Please return -1 if any row or any column has multiple minimum or maximum elements.

For example, given a matrix of size 3*3, the elements are stored as follows.

1  3  4
5  2  9
8  7  6

The expected output is 7.

In the above example, we identified the output as 7 based on below.

1 - minimum in row and column
4 - Maximum in row
2 - Minimum in column and row
9 - Maximum in row and column
8 - Maximum in row and column
7 - Maximum in column
6 - Minimum in row

Input:

m - integer - number of rows
n - integer - number of columns
m * n matrix

Output:

r - integer - result

Constraints:

0<m,n<100
Elements in the matrix are positive integers.

Programming Solution in Python:

#!/bin/python3

import math
import os
import random
import re
import sys

# Complete the countSpecialElements function below.

def countSpecialElements(matrix):
  nRows= len(matrix)
  nCount=0

  for row in matrix:
    for indexCol, element in enumerate(row):

      if element==min(row) or element==max(row):
          if row.count(element)>1:
              return -1
          nCount=nCount+1

      else:
        listColumn=[]

        for indexRow in range(0,nRows):
          listColumn.append(matrix[indexRow][indexCol])

          if element==min(listColumn) or element==max(listColumn):
            if listColumn.count(element)>1:
              return -1
            nCount=nCount+1

  return nCount

if __name__ == '__main__':
  countSpecialElements([[1, 3, 4],[5, 2, 9],[8, 7, 6]])

Output:

7

In Python, matrix elements are stored as a nested list. To solve this kind of problems, you should have a good understanding of the list and its methods.

If you are solving this coding question in a competitive test round, consider all boundary cases.

There was one more question was asked in Goldman Sachs coding round- Secure My Conversation.