Distribute Candies

https://leetcode.com/problems/distribute-candies/description/

Given an integer array with even length, where different numbers in this array represent different kinds of candies. Each number means one candy of the corresponding kind. You need to distribute these candies equally in number to brother and sister. Return the maximum number of kinds of candies the sister could gain.

Example 1:

Input: candies = [1,1,2,2,3,3]

Output: 3

Explanation:

There are three different kinds of candies (1, 2 and 3), and two candies for each kind.

Optimal distribution: The sister has candies [1,2,3] and the brother has candies [1,2,3], too.

The sister has three different kinds of candies.

Example 2:

Input: candies = [1,1,2,3]

Output: 2

Explanation: For example, the sister has candies [2,3] and the brother has candies [1,1].

The sister has two different kinds of candies, the brother has only one kind of candies.

Thoughts

这题最难的点在于弄懂要干什么。偶数个数字，每个数字代表一种糖。要选出一半的糖，使得种类尽可能的多。那么每种糖选一个自然种类就最多了。

Code

class Solution {
    public int distributeCandies(int[] candies) {
        Set<Integer> cand = new HashSet<>();
        for (int i = 0; i < candies.length; i++) {
            cand.add(candies[i]);
        }
        if (cand.size() > candies.length / 2) {
            return candies.length / 2;
        } else {
            return cand.size();
        }
    }
}

Analysis

时间复杂度O(n).