LeetCode-Find the Celebrity

Posted LiBlog

tags:

篇首语:本文由小常识网(cha138.com)小编为大家整理,主要介绍了LeetCode-Find the Celebrity相关的知识,希望对你有一定的参考价值。

Suppose you are at a party with n people (labeled from 0 to n - 1) and among them, there may exist one celebrity. The definition of a celebrity is that all the other n - 1 people know him/her but he/she does not know any of them.

Now you want to find out who the celebrity is or verify that there is not one. The only thing you are allowed to do is to ask questions like: "Hi, A. Do you know B?" to get information of whether A knows B. You need to find out the celebrity (or verify there is not one) by asking as few questions as possible (in the asymptotic sense).

You are given a helper function bool knows(a, b) which tells you whether A knows B. Implement a function int findCelebrity(n), your function should minimize the number of calls to knows.

Note: There will be exactly one celebrity if he/she is in the party. Return the celebrity‘s label if there is a celebrity in the party. If there is no celebrity, return -1.

Solution:

/* The knows API is defined in the parent class Relation.
      boolean knows(int a, int b); */

public class Solution extends Relation {
    public int findCelebrity(int n) {
        int candidate = 0;
        for (int i=1;i<n;i++)
            if (knows(candidate,i)){
                candidate = i;
            }
        
        for (int i=0;i<n;i++)
            if (i!=candidate && (knows(candidate,i) || !knows(i,candidate))) return -1;
        
        return candidate;
    }
}

 

以上是关于LeetCode-Find the Celebrity的主要内容,如果未能解决你的问题,请参考以下文章

LeetCode-Find Median from Data Stream

leetcode-Find Peak Element-162

leetCode-Find All Numbers Disappeared in an Array

leetcode-Find Minimum in Rotated Sorted Array-153

leetcode-Find Minimum in Rotated Sorted Array II-154

The goddess, the bird, the bell, the temptation of the house