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Problem: Find the Town Judge

easy
15 min
Explore how to determine the town judge by applying graph theory concepts to trust data. Understand the problem constraints and implement efficient solutions to solve this common coding interview question.

Statement

There are n people numbered from 11 to n in a town. There’s a rumor that one of these people is secretly the town judge. A town judge must meet the following conditions:

  1. The judge doesn’t trust anyone.

  2. Everyone else in the town (except the town judge) trusts the judge.

  3. There is exactly one person who fulfills both the above conditions.

You are given an integer n and a two-dimensional array, trust, where each entry trust[i]=[ai,bi]trust[i] = [a_i, b_i] indicates that the person labeled aia_i trusts the person labeled bib_i. If a trust relationship is not specified in the trust array, it does not exist. Your task is to determine the label of the town judge, if one can be identified. If no such person exists, return 1-1.

Constraints:

  • 11 \leqn 1000\leq 1000

  • 00 \leqtrust.length 104\leq 10^{4}

  • trust[i].length ==2 == 2

  • ai \ne bi

  • 11 \leqai , bi \leqn

  • All the pairs in trust are unique.

Tap here to switch tabs
Problem
Ask
Submissions

Problem: Find the Town Judge

easy
15 min
Explore how to determine the town judge by applying graph theory concepts to trust data. Understand the problem constraints and implement efficient solutions to solve this common coding interview question.

Statement

There are n people numbered from 11 to n in a town. There’s a rumor that one of these people is secretly the town judge. A town judge must meet the following conditions:

  1. The judge doesn’t trust anyone.

  2. Everyone else in the town (except the town judge) trusts the judge.

  3. There is exactly one person who fulfills both the above conditions.

You are given an integer n and a two-dimensional array, trust, where each entry trust[i]=[ai,bi]trust[i] = [a_i, b_i] indicates that the person labeled aia_i trusts the person labeled bib_i. If a trust relationship is not specified in the trust array, it does not exist. Your task is to determine the label of the town judge, if one can be identified. If no such person exists, return 1-1.

Constraints:

  • 11 \leqn 1000\leq 1000

  • 00 \leqtrust.length 104\leq 10^{4}

  • trust[i].length ==2 == 2

  • ai \ne bi

  • 11 \leqai , bi \leqn

  • All the pairs in trust are unique.