## Algorithm

Problem Name: 997. Find the Town Judge

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`. 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
```

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`

## Code Examples

### #1 Code Example with Java Programming

```Code - Java Programming```

``````
class Solution {
public int findJudge(int n, int[][] trust) {
int[] trustScore = new int[n + 1];
for (int[] trustPair : trust) {
trustScore[trustPair]++;
trustScore[trustPair]--;
}
for (int i = 1; i <= n; i++) {
if (trustScore[i] == n - 1) {
return i;
}
}
return -1;
}
}
``````
Copy The Code &

Input

cmd
n = 2, trust = [[1,2]]

Output

cmd
2

### #2 Code Example with Javascript Programming

```Code - Javascript Programming```

``````
const findJudge = function(N, trust) {
const arr = new Array(N + 1).fill(0)
for(let [t, ted] of trust) {
arr[t]--
arr[ted]++
}
for(let i = 1; i <= N; i++) {
if(arr[i] === N - 1) return i
}
return -1
};
``````
Copy The Code &

Input

cmd
n = 2, trust = [[1,2]]

Output

cmd
2

### #3 Code Example with Python Programming

```Code - Python Programming```

``````
class Solution:
def findJudge(self, N: int, trust: List[List[int]]) -> int:
j, cnt = collections.Counter(b for a, b in trust).most_common(1) if trust else (N, 0)
return j if j not in {a for a, b in trust} and cnt == N - 1 else -1
``````
Copy The Code &

Input

cmd
n = 3, trust = [[1,3],[2,3]]

Output

cmd
3

### #4 Code Example with C# Programming

```Code - C# Programming```

``````
namespace LeetCode
{
public class _0997_FindTheTownJudge
{
public int FindJudge(int N, int[][] trust)
{
var score = new int[N + 1];
foreach (var pair in trust)
{
score[pair]--;
score[pair]++;
}

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

return -1;
}
}
}
``````
Copy The Code &

Input

cmd
n = 3, trust = [[1,3],[2,3]]

Output

cmd
3