Grokking the Coding Interview: Patterns for Coding Questions
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Number of Provinces (medium)
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Problem Statement

Examples

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Problem Statement

There are n cities. Some of them are connected in a network. If City A is directly connected to City B, and City B is directly connected to City C, city A is indirectly connected to City C.

If a group of cities are connected directly or indirectly, they form a province.

Given an n x n matrix isConnected where isConnected[i][j] = 1 if the i<sup>th</sup> city and the j<sup>th</sup> city are directly connected, and isConnected[i][j] = 0 otherwise, determine the total number of provinces.

Examples

  • Example 1:
    • Input: isConnected = [[1,1,0],[1,1,0],[0,0,1]]
Image

  • Expected Output: 2

  • Justification: Here, city 1 and 2 form a single provenance, and city 3 is one provinces itself.

  • Example 2:

    • Input: isConnected = [1,0,0],[0,1,0],[0,0,1]]
Image

  • Expected Output: 3

  • Justification: In this scenario, no cities are connected to each other, so each city forms its own province.

  • Example 3:

    • Input: isConnected = [[1,0,0,1],[0,1,1,0],[0,1,1,0],[1,0,0,1]]
Image
  • Expected Output: 2
  • Justification: Cities 1 and 4 form a province, and cities 2 and 3 form another province, resulting in a total of 2 provinces.

Constraints:

  • 1 <= n <= 200
  • n == isConnected.length
  • n == isConnected[i].length
  • isConnected[i][j] is 1 or 0.
  • isConnected[i][i] == 1
  • isConnected[i][j] == isConnected[j][i]

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Python3
Python3
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On this page

Problem Statement

Examples

Try it yourself