Leetcode•Feb 20, 2026

Find the Town Judge

Hazrat Ali

Leetcode

If the town judge exists, then:

  1. The town judge trusts nobody.
  2. Everybody (except for the town judge) trusts the town judge.
  3. There is exactly one person that satisfies properties 1 and 2.

You are given an array trust where trust[i] = [ai, bi] representing that the person labeled ai trusts the person labeled bi. If a trust relationship does not exist in trust array, then such a trust relationship does not exist.

Return the label of the town judge if the town judge exists and can be identified, or return -1 otherwise.

 

Example 1:

Input: n = 2, trust = [[1,2]]
Output: 2

Example 2:

Input: n = 3, trust = [[1,3],[2,3]]
Output: 3

Example 3:

Input: n = 3, trust = [[1,3],[2,3],[3,1]]
Output: -1

Solution
var findJudge = function(n, trust) {
    let score = new Array(n + 1).fill(0);

    for (let [a, b] of trust) {
        score[a]--;  
        score[b]++;  
    }

    for (let i = 1; i <= n; i++) {
        if (score[i] === n - 1) {
            return i;
        }
    }

    return -1;
};



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