## 题目

In a town, there are `N`

people labelled from `1`

to `N`

. There is a rumor that one of these people is secretly the town judge.

If the town judge exists, then:

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

You are given `trust`

, an array of pairs `trust[i] = [a, b]`

representing that the person labelled `a`

trusts the person labelled `b`

.

If the town judge exists and can be identified, return the label of the town judge. Otherwise, return `-1`

.

Example 1:

1 | Input: N = 2, trust = [[1,2]] |

Example 2:

1 | Input: N = 3, trust = [[1,3],[2,3]] |

Example 3:

1 | Input: N = 3, trust = [[1,3],[2,3],[3,1]] |

Example 4:

1 | Input: N = 3, trust = [[1,2],[2,3]] |

Example 5:

1 | Input: N = 4, trust = [[1,3],[1,4],[2,3],[2,4],[4,3]] |

**Note:**

`1 <= N <= 1000`

`trust.length <= 10000`

`trust[i]`

are all different`trust[i][0] != trust[i][1]`

`1 <= trust[i][0], trust[i][1] <= N`

## 思路

Easy题打卡，图的入度和出度。

法官就是入度为N-1，出度为0的节点。

## 代码

1 | class Solution(object): |