LeetCode 575. Distribute Candies

一、题目描述

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.

二、解题思路

题目的意思是兄妹两人要分得相同数目的糖，但是妹妹分到的糖的种类要尽可能多，其实只需尽可能把所有种类的糖果都分给妹妹，因此我们并不需要知道每种糖果的数量，只需要知道一共有多少种糖果，因此使用元素不重复的set来存储所有糖果，那么set的大小就是糖果种类的多少。
由于兄妹两人是平分糖果的，那么如果糖果种类n多于糖果数量m的一半，那么妹妹可以得到m/2种糖果；如果糖果种类m小于糖果数量m的一半，那么妹妹可以得到n种糖果

三、C++代码

class Solution {public:    int distributeCandies(vector<int>& candies) {        set<int> kinds;        for (int i = 0; i < candies.size(); i++) {            kinds.insert(candies[i]);        }        if (kinds.size() >= candies.size() / 2)            return candies.size() / 2;        return kinds.size();    }};