FindingCelebrity.java

package com.interview.misc;

/**
 * Find the Celebrity
 * https://leetcode.com/problems/find-the-celebrity/
 */
class Relation {
    boolean knows(int a, int b) {
        return false;
    }
}

public class FindingCelebrity extends Relation {

    public int findCelebrity(int n) {
        int celebrity = 0;
        for (int i = 1; i < n; i++) {
            if (knows(celebrity, i)) {
                celebrity = i;
            }
        }
        for (int i = 0; i < n; i++) {
            if (i == celebrity) {
                continue;
            }
            if (knows(celebrity, i) || !knows(i, celebrity)) {
                return -1;
            }
        }
        return celebrity;
    }
}