算法作业_31(2017.6.14第十七周)

455. 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 g_i, which is the minimum size of a cookie that the child will be content with; and each cookie j has a size s_j. If s_j >= g_i, 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.

解析：一个简单的贪心算法，先对两个数组经行排序，使其从大到小排列，然后依次用最大的饼干去比较最贪心的同学，如果最大的饼干小于他的贪心指数，则res++；否则比较下一个同学：

class Solution {public:    int findContentChildren(vector<int>& g, vector<int>& s) {        sort(g.begin(),g.end(),greater<int>());        sort(s.begin(),s.end(),greater<int>());        int si = 0 , gi = 0 ;        int res = 0;        while(si<s.size() && gi<g.size()){            if(s[si]>=g[gi]){                res ++;                si++;                gi++;            }else{                gi++;            }        }        return res ;     }};