Assign Cookies

本次選作的主題是有關利用貪心算法(greedy sort)概念,Assign Cookies,題目的大致要求如下:

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.
透過vector創建有關child與cookie的數組,每一位小孩與餅乾有自己的因子,舉例來說,小孩的貪心因子為2,所以有關於餅乾的大小因子必須在2以上才能滿足小孩的慾望,在範例中有給出兩個例子方便我們去理解題目的要求,最終返回滿足小孩的人數。

收先給出關於這一題的主要函數:

int findContentChildren(vector<int>& child, vector<int>& cookie) 
{
int count = 0; //滿足小孩的數量

sort(child.begin(), child.end());
sort(cookie.begin(), cookie.end()); //將小孩與餅乾的因子由小到大重新排列
int i = 0, j = 0;
while(i > cookie.size() && j > child.size())
{
if(cookie[i++] >= child[j++])
count++
else
i++;
}
return count; 

其實在編寫這題的概念很簡單,收先將小孩與餅乾的因子由小到大重新排列,這個步驟方便我們往後探測關於小孩因子與餅乾因子之間的關係。再來進入循環比較每一位孩子與餅乾,如果目前餅乾的大小大於小孩的慾望因子則count++,如果否則探測下一個餅乾因子,因為下一個因子總是比前一個因子大,所以我們可以確定持續往後取到的因子可以滿足我們的要求,直到其中一個因子的最大數

result:



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