leetcode 455. Assign Cookies（python）

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 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.

Example 1:

Input: g = [1,2,3], s = [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: g = [1,2], s = [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.

Note:

1 <= g.length <= 3 * 10^4
0 <= s.length <= 3 * 10^4
1 <= g[i], s[j] <= 2^31 - 1

解析

根据题意，就是有蛋糕尺寸列表 s ，孩子得到满足的最小蛋糕尺寸列表 g ，只能给每个孩子最多一个蛋糕，并且要达到其满足的最小蛋糕尺寸才行，找出得到满足的孩子有几个。先将 g 和 s 进行排序，然后遍历 g 和 s ，如果某蛋糕满足孩子的蛋糕尺寸要求，则将该蛋糕去掉，并且结果加 1 ，遍历结束即可得到答案。

解答

class Solution(object):
    def findContentChildren(self, g, s):
        """
        :type g: List[int]
        :type s: List[int]
        :rtype: int
        """
        r = 0
        g.sort()
        s.sort()
        for i,v in enumerate(g):
            for j,c in enumerate(s):
                if v<=c:
                    s.pop(j)
                    r+=1
                    break
        return r

运行结果

Runtime: 1088 ms, faster than 10.12% of Python online submissions for Assign Cookies.
Memory Usage: 14.7 MB, less than 94.16% of Python online submissions for Assign Cookies.

解析

上面的双重循环太耗时间，可以只用一重循环找到答案，定义 i 表示 g 的索引，res 表示结果。现将 g 和 s 进行排序，然后遍历 s ，如果 g 为空表示没有孩子列表，则直接返回结果 0 。否则如果当前尺寸满足孩子要求时，结果加 1 ，i 也加 1 。继续循环上述操作，遍历结束会得到结果。

解答

class Solution(object):
    def findContentChildren(self, g, s):
        """
        :type g: List[int]
        :type s: List[int]
        :rtype: int
        """
        g.sort()
        s.sort()
        res = 0
        i = 0
        for e in s:
            if i == len(g):
                break
            if e >= g[i]:
                res += 1
                i += 1
        return res

运行结果

Runtime: 124 ms, faster than 98.83% of Python online submissions for Assign Cookies.
Memory Usage: 14.9 MB, less than 54.09% of Python online submissions for Assign Cookies.

原题链接：https://leetcode.com/problems/assign-cookies/

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