Leetcode
2020.05.02 18:25

997. Find the Town Judge

조회 수 686 추천 수 0 댓글 0
?

단축키

Prev이전 문서

Next다음 문서

크게 작게 위로 아래로 댓글로 가기 인쇄
?

단축키

Prev이전 문서

Next다음 문서

크게 작게 위로 아래로 댓글로 가기 인쇄

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


aclass Solution {
    public int findJudge(int N, int[][] trust) {
        Map<Integer, Integer> hmap = new HashMap<>();
        
        if(trust.length == 0){
            return 1;
        }
        
        for(int i=0; i<trust.length; i++){
            Integer people = trust[i][0];
            Integer tpeople = trust[i][1];
            
            hmap.put(people, hmap.getOrDefault(people,0)-1);
            hmap.put(tpeople, hmap.getOrDefault(tpeople,0)+1);
        }
        
        for(Map.Entry<Integer, Integer> item : hmap.entrySet()){
            Integer tpeople = item.getKey();
            Integer tcount = item.getValue();
            
            if(tcount == N - 1){
                return tpeople;
            }
        }
        
        return -1;
    }
}


class Solution {
    public int findJudge(int N, int[][] trust) {
        int[] trusted = new int[N];
        
        for(int i=0; i<trust.length; i++){
            int people = trust[i][0];
            int tpeople = trust[i][1];
            trusted[tpeople-1]++;
            trusted[people-1]--;
        }
        
        for(int i=0; i<trusted.length; i++){
            if(trusted[i] == N - 1){
                return i+1;
            }
        }
        
        return -1;
    }
}

[문제] https://leetcode.com/problems/find-the-town-judge/


?

List of Articles
번호 분류 제목 글쓴이 날짜 조회 수
77 Leetcode 720. Longest Word in Dictionary hooni 2020.05.07 812
76 Leetcode 225. Implement Stack using Queues hooni 2020.05.05 707
75 Leetcode 56. Merge Intervals hooni 2020.05.05 658
74 Leetcode 844. Backspace String Compare hooni 2020.05.05 705
73 Leetcode 222. Count Complete Tree Nodes hooni 2020.05.05 681
72 Leetcode 697. Degree of an Array hooni 2020.05.05 755
71 Leetcode 605. Can Place Flowers hooni 2020.05.05 667
70 Leetcode 724. Find Pivot Index hooni 2020.05.05 689
69 Leetcode 448. Find All Numbers Disappeared in an Array hooni 2020.05.05 641
68 Leetcode 628. Maximum Product of Three Numbers hooni 2020.05.05 640
67 Leetcode 532. K-diff Pairs in an Array hooni 2020.05.04 695
66 Leetcode 897. Increasing Order Search Tree hooni 2020.05.04 657
65 Leetcode 872. Leaf-Similar Trees file hooni 2020.05.04 648
64 Leetcode 876. Middle of the Linked List hooni 2020.05.04 646
63 Leetcode 203. Remove Linked List Elements hooni 2020.05.04 620
» Leetcode 997. Find the Town Judge hooni 2020.05.02 686
61 Leetcode 270. Closest Binary Search Tree Value hooni 2020.05.01 623
60 Leetcode 687. Longest Univalue Path hooni 2020.05.01 689
59 Leetcode 783. Minimum Distance Between BST Nodes hooni 2020.05.01 700
58 Leetcode 235. Lowest Common Ancestor of a Binary Search Tree file hooni 2020.05.01 689
Board Pagination Prev 1 2 3 4 Next
/ 4