LeetCode 575. Distribute Candies （发糖果）

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. 

Note:

1. The length of the given array is in range [2, 10,000], and will be even.
2. The number in given array is in range [-100,000, 100,000].

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 题目标签：HashTable

　　这道题目给了我们一个糖果array， 里面的每一个数字代表了一种种类的糖。要求我们找出sister可以拿到最多种类的糖的数量。那么我们来看一下，给的糖果一定是偶数的，那么sister可以拿到的数量一定是 candies.length / 2, 糖果总数的一半。接下来有两种可能性会发生，1 - 如果sister糖果的数量 大于等于 糖果的种类数量， 那么 sister最多可以拿到的糖果种类数量就等于，糖果的种类数量；2 - 如果sister糖果的数量 小于 糖果的种类数量， 那么sister最多可以拿到的糖果种类数量 就等于 她自己的糖果的数量。

 

Java Solution:

Runtime beats 90.78% 

完成日期：06/07/2017

关键词：HashMap

关键点：分析可能性

public class Solution 
{
    public int distributeCandies(int[] candies) 
    {
        HashSet<Integer> set = new HashSet<>();
        
        for(int i=0; i<candies.length; i++)
            set.add(candies[i]);
        
        // if candy number for sister >= the number of kinds for candies -> kinds
        // if candy number for sister < the number of kinds for candies -> candy number
        return Math.min(set.size(), candies.length/2);
    }
}

参考资料：N/A

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