LeetCode 455. Assign Cookies (C++)

题目：

Assume you are an awesome parent and want to give your children some cookies. But, you should give each child at most one cookie. Each child i has a greed factor gi, which is the minimum size of a cookie that the child will be content with; and each cookie j has a size sj. If sj >= gi, we can assign the cookie j to the child i, and the child i will be content. Your goal is to maximize the number of your content children and output the maximum number.

Note:
You may assume the greed factor is always positive. 
You cannot assign more than one cookie to one child.

Example 1:

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

Output: 1

Explanation: You have 3 children and 2 cookies. The greed factors of 3 children are 1, 2, 3. 
And even though you have 2 cookies, since their size is both 1, you could only make the child whose greed factor is 1 content.
You need to output 1.

 

Example 2:

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

Output: 2

Explanation: You have 2 children and 3 cookies. The greed factors of 2 children are 1, 2. 
You have 3 cookies and their sizes are big enough to gratify all of the children, 
You need to output 2.

分析：

有两个数组，分别代表孩子需要曲奇的大小，和你所拥有曲奇的大小，求最大满足孩子的数目。

经典的贪心问题，我们可以这样想，如果一个曲奇不能满足当前这个孩子的话，那么一定不能满足比这个孩子还要大的尺寸。我们还希望满足一个孩子曲奇的尺寸尽量和他需要的接近，也就是不要浪费大尺寸的曲奇。所以我们可以先将两个数组有小到大排序。遍历曲奇数组，如果当前这个曲奇不满足第一个孩子，那么就看下一个曲奇。如果满足，则数目加一，并且孩子和曲奇的指针也同时加一。这样可以满足我们上面提到的两个要求。

程序：

class Solution {
public:
    int findContentChildren(vector<int>& g, vector<int>& s) {
        sort(g.begin(), g.end());
        sort(s.begin(), s.end());
        int sum = 0;
        int i = 0;
        int j = 0;
        while(i < g.size() && j < s.size()){
            while(j < s.size()){
                if(g[i] <= s[j]){
                    sum++;
                    j++;
                    break;
                }
                j++;
            }
            i++;
        }
        return sum;
    }
};