-
Notifications
You must be signed in to change notification settings - Fork 4
Expand file tree
/
Copy pathFindTheTownJudge.java
More file actions
103 lines (99 loc) · 2.66 KB
/
Copy pathFindTheTownJudge.java
File metadata and controls
103 lines (99 loc) · 2.66 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
package algorithms;
/**
* 997. Find the Town Judge
* https://leetcode.com/problems/find-the-town-judge/
* Difficulty : Easy
* Related Topics : Graph
*
* 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:
*
* 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
*
*
* Constraints:
*
* 1 <= N <= 1000
* 0 <= trust.length <= 10^4
* trust[i].length == 2
* trust[i] are all different
* trust[i][0] != trust[i][1]
* 1 <= trust[i][0], trust[i][1] <= N
*
* created by cenkc on 8/10/2020
*/
public class FindTheTownJudge {
public static void main(String[] args) {
/*
Input: N = 1, trust = []
Output: 1
Input: N = 2, trust = [[1,2]]
Output: 2
Input: N = 3, trust = [[1,3],[2,3]]
Output: 3
Input: N = 3, trust = [[1,3],[2,3],[3,1]]
Output: -1
Input: N = 3, trust = [[1,2],[2,3]]
Output: -1
Input: N = 4, trust = [[1,3],[1,4],[2,3],[2,4],[4,3]]
Output: 3
*/
int N = 3;
int[][] trust = new int[][] {
{1, 3},
{2, 3}
};
FindTheTownJudge townJudge = new FindTheTownJudge();
System.out.println(townJudge.findJudge(N, trust));
}
/**
* Runtime: 3 ms, faster than 90.90% of Java online submissions for Find the Town Judge.
* Memory Usage: 47.1 MB, less than 76.55% of Java online submissions for Find the Town Judge.
*
* @param N
* @param trust
* @return
*/
public int findJudge(int N, int[][] trust) {
int[] count = new int[N + 1]; // because N starts from 1
for (int[] t : trust) {
count[t[0]]--;
count[t[1]]++;
}
for (int i = 1; i <= N; i++) {
if (count[i] == N-1) { // everyone trusts the judge, except the judge himself
return i;
}
}
return -1;
}
}