1338. Reduce Array Size to The Half - kumaeki/LeetCode GitHub Wiki
1338. Reduce Array Size to The Half
Given an array arr. You can choose a set of integers and remove all the occurrences of these integers in the array.
Return the minimum size of the set so that at least half of the integers of the array are removed.
Example 1:
Input: arr = [3,3,3,3,5,5,5,2,2,7]
Output: 2
Explanation: Choosing {3,7} will make the new array [5,5,5,2,2] which has size 5 (i.e equal to half of the size of the old array).
Possible sets of size 2 are {3,5},{3,2},{5,2}.
Choosing set {2,7} is not possible as it will make the new array [3,3,3,3,5,5,5] which has size greater than half of the size of the old array.
Example 2:
Input: arr = [7,7,7,7,7,7]
Output: 1
Explanation: The only possible set you can choose is {7}. This will make the new array empty.
Example 3:
Input: arr = [1,9]
Output: 1
Example 4:
Input: arr = [1000,1000,3,7]
Output: 1
Example 5:
Input: arr = [1,2,3,4,5,6,7,8,9,10]
Output: 5
Constraints:
- 1 <= arr.length <= 10^5
- arr.length is even.
- 1 <= arr[i] <= 10^5
按照每个数字出现的次数从大降序排序, 然后依次抽出来相加算总数就好了.
class Solution {
public int minSetSize(int[] arr) {
Map<Integer, Integer> map = new HashMap<>();
for(int n : arr)
map.put(n, map.getOrDefault(n, 0) + 1);
PriorityQueue<Integer> que = new PriorityQueue<>((a, b) -> b - a);
for(int v : map.values())
que.add(v);
int result = 0, sum = 0, len = arr.length / 2;
while(sum < len){
sum += que.poll();
result++;
}
return result;
}
}