【两次过】Lintcode 1230. Assign Cookies

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.

样例

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.

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解题思路：

贪心算法。先将两数组降序排序，然后看最大的饼干能不能满足最贪婪的小朋友，如果能则res++，考察下一组元素，如果不能满足，则考察下一位小朋友能不能满足。

class Solution {
public:
    /**
     * @param g: children's greed factor
     * @param s: cookie's size
     * @return: the maximum number
     */
    int findContentChildren(vector<int> &g, vector<int> &s)
    {
        // Write your code here
        sort(g.begin() , g.end() , greater<int>());
        sort(s.begin() , s.end() , greater<int>());
        
        int si = 0 , gi = 0;//si指向当前饼干，gi指向当前小朋友
        int res = 0;
        
        while(si < s.size() && gi < g.size())
        {
            if(s[si] >= g[gi])
            {
                res++;
                si++;
                gi++;
            }
            else
                gi++;
        }
        
        return res;
    }
};