Assign Cookies(算法分析week7)

Assign Cookies

題目來源：https://leetcode.com/problemset/algorithms/
題目類型：貪心算法

-問題描述-
-解題思路-
-代碼實現-

問題描述

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.

解題思路

爲了實現用一定的數量和大小的cookie滿足儘量多的孩子，那麼要求儘可能滿足需求小的孩子。
(1)首先可以將cookie和children的數組按照升序排序。
(2)對於當前需求最小的孩子，找到滿足其需求的最小的cookie. i指向children的數組從前往後遍歷，j指向cookie的數組從前往後遍歷。如果cookie[j] >= children[i], i++, j++;否則 j++
(3)i的大小即爲可滿足孩子的最大數目。

代碼實現

@requires_authorization
class Solution {
public: 
    int findContentChildren(vector<int>& g, vector<int>& s) {
        int sum = 0;
        int i = 0, j = 0;
        sort(s.begin(), s.end());
        sort(g.begin(), g.end());
        while (i != g.size()&&j != s.size()) {
            if (g[i] <= s[j]) {
                i++;
                j++;
                sum++;
            } else 
                j++;
        }
        return sum;
    }
};