Leetcode: 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.

Solution 1: Greedy, Time:O(nlogn)

Just assign the cookies starting from the child with less greediness to maximize the number of happy children .

 public class Solution {
     public int findContentChildren(int[] g, int[] s) {
         Arrays.sort(g);
         Arrays.sort(s);
         int i = 0;
         for (int j=0; i<g.length && j<s.length; j++) {
             if (g[i] <= s[j]) i++;
         }
         return i;
     }
 }

Solution 2: Greedy + TreeMap,   Time: O(nlogm), n, m are the size of two arrays respectively

 public class Solution {
     public int findContentChildren(int[] g, int[] s) {
         TreeMap<Integer, Integer> map = new TreeMap<Integer, Integer>();
         int res = 0;
         for (int size : s) {
             map.put(size, map.getOrDefault(size, 0)+1);
         }

         for (int greed : g) {
             if (map.ceilingKey(greed) != null) {
                 res++;
                 int value = map.ceilingKey(greed);
                 map.put(value, map.get(value)-1);
                 if (map.get(value) == 0) map.remove(value);
             }
         }
         return res;
     }
 }