# 997. Find the Town Judge

#### Easy

***

In a town, there are `n` people labeled from `1` to `n`. There is a rumor that one of these people is secretly the town judge.

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`.

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
```

 

**Constraints:**

* `1 <= n <= 1000`
* `0 <= trust.length <= 104`
* `trust[i].length == 2`
* All the pairs of `trust` are **unique**.
* `ai != bi`
* `1 <= ai, bi <= n`

```python
class Solution:
    def findJudge(self, n: int, trust: List[List[int]]) -> int:
        inDegree = [0]*n
        outDegree = [0]*n
        for a,b in trust:
            outDegree[a-1] += 1
            inDegree[b-1] += 1
        index = 0
        # print(inDegree)
        # print(outDegree)
        for degree in inDegree:
            if degree == (n-1):
                if outDegree[index] == 0:
                    return (index+1)
            index += 1
        return -1
```