997. Find the Town Judge

#### QUESTION:

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:

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 `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:

``````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
``````

Example 4:

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

Example 5:

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

Note:

1. `1 <= N <= 1000`
2. `trust.length <= 10000`
3. `trust[i]` are all different
4. `trust[i][0] != trust[i][1]`
5. `1 <= trust[i][0], trust[i][1] <= N`

#### SOLUTION:

``````class Solution {
public int findJudge(int N, int[][] trust) {
if(trust.length==0) return 1;
int[][] result = new int[N+1][2];
for(int i=0;i<trust.length;i++){
result[trust[i][0]][0]++;//信任别人个数
result[trust[i][1]][1]++;//被信任个数
}
for(int i = 0;i<result.length;i++){
if(result[i][0]==0 && result[i][1]==N-1) return i;
}
return -1;
}
}
``````