LeetCode455 Assign Cookies


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.

样例

Example 1:

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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:

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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.

思路

有n个小朋友和m块饼干,第i个小朋友至少要g[i]大小的饼干,而第i块饼干大小为s[i],每个小朋友只能分到一块饼干,问分掉这些饼干最多能让多少个小朋友满意。

先把小朋友的需求以及饼干的大小按递增排个序。基于贪心的思想,饼干能早分掉就尽早分掉,在排完序后,如果第j块饼能满足第i个小朋友,那么肯定也能满足前i-1个小朋友,因此把饼干早分掉不会使结果变得更差。(早分掉的意思是一旦当前饼干能满足当前小朋友的需求,就分给他,而不必把饼干留到后面分)

代码

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class Solution {
public:
int findContentChildren(vector<int>& g, vector<int>& s) {
sort(g.begin(), g.end());
sort(s.begin(), s.end());
int p1 = 0, p2= 0, ans = 0;
while (p1 < g.size() && p2 < s.size()) {
if (g[p1] <= s[p2]) p1++, ans++;
p2++;
}
return ans;
}
};