[LeetCode]Assign Cookies

题目描述:

LeetCode 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 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.

题目大意:

假设你是一位很赞的家长想要给孩子一些饼干。但是,你只能至多给每个孩子一个饼干。孩子i的贪婪因子为gi,意思是他所满意的饼干的最小尺寸;每一个饼干j的尺寸为sj。如果sj >= gi,我们就可以把饼干j分给孩子i,然后孩子i会很满意。你的目标是最大化分到饼干的孩子的个数。

注意:

可以假设贪婪因子都是正数。

不可以为一个孩子分配多个饼干。

解题思路:

贪心算法(Greedy Algorithm)

首先对贪婪系数g、饼干尺寸s从小到大排序

令指针i指向g的末尾,指针j指向s的末尾

当g和s均≥0时,执行循环:

  若g[i] ≤ s[j] 则令计数器+1,并令j -= 1 (将j号饼干分配给i号孩子,并令j指向下一个更小的饼干)

  令i -= 1 (将i指向下一个贪婪系数更小的孩子)

Python代码:

class Solution(object):
    def findContentChildren(self, g, s):
        """
        :type g: List[int]
        :type s: List[int]
        :rtype: int
        """
        cnt = 0
        i, j = len(g) - 1, len(s) - 1
        g, s = sorted(g), sorted(s)
        while min(i, j) >= 0:
            if g[i] <= s[j]:
                cnt += 1
                j -= 1
            i -= 1
        return cnt

 

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