LeetCode455. Assign Cookies

题目描述：

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.

题目解答：该题目很明显是一个贪心问题，对于贪心问题，一是要optimal structure，二是具有greedy selection贪心选择策略。对于该题，可以考虑先对两个数组进行排序，双指针i和j，保证指针i,j前的数组是当前能够满足的最大孩子数。

python代码：

class Solution:
    def findContentChildren(self, g, s):
        """
        :type g: List[int]
        :type s: List[int]
        :rtype: int
        """
        if not g:
            return 0
        g.sort()
        s.sort()
        res = 0
        i, j = 0, 0
        while i < len(g) and j < len(s):
            if s[j] >= g[i]:
                res += 1
                i += 1
            j += 1
        return res