《算法分析与设计》Week 6

455. Assign Cookies

Description:

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: 1Explanation: 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: 2Explanation: 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.

Solution:

一、题意理解

     你是位很好的父亲，有一堆孩子，和一堆饼干。饼干的大小不同，不同孩子对饼干大小的“满足度”不同，每个孩子最多只能分一个饼干，你要做的就是怎么分配饼干，可以使得尽可能多的孩子满足。

二、分析

     1、典型的贪心算法问题，可以先对孩子们“满足度”和饼干大小进行排序，从小到大进行遍历，如果当前饼干可以满足某个孩子，就分配给他，不能的话，就遍历下一个较大的饼干，以此类推。核心分配方法就是尽可能使用最小的饼干满足某个孩子。

     2、代码如下：

class Solution {public:    int findContentChildren(vector<int>& g, vector<int>& s) {        sort(g.begin(), g.end());        sort(s.begin(), s.end());                int result = 0;        vector<int>::iterator gi = g.begin(), si = s.begin();        while(gi != g.end() && si < s.end())        {            if(*si >= *gi)            {                result++;                si++;                gi++;            }            else                si++;        }        return result;    }};