Leetcode 2341. How many pairs can an array form

1. subject

I'll give you a subscript from 0 The starting array of integers nums . In one step , You can do the following ：

• from nums elect Two equal Integers
• from nums Remove these two integers , To form a Number pair

Please come in nums Perform this operation several times on until it cannot be continued .

Returns a subscript from 0 Start 、 The length is 2 Array of integers for answer As the answer , among answer[0] Is the number of pairs formed ,answer[1] It's right nums Try to count the number of integers left after the above operation .

 Example  1：
 Input ：nums = [1,3,2,1,3,2,2]
 Output ：[3,1]
 explain ：
nums[0]  and  nums[3]  Form a number pair , And from  nums  Remove ,nums = [3,2,3,2,2] .
nums[0]  and  nums[2]  Form a number pair , And from  nums  Remove ,nums = [2,2,2] .
nums[0]  and  nums[1]  Form a number pair , And from  nums  Remove ,nums = [2] .
 Cannot form more pairs . A total of  3  Pairs of numbers ,nums  The rest of the world is  1  A digital .

 Example  2：
 Input ：nums = [1,1]
 Output ：[1,0]
 explain ：nums[0]  and  nums[1]  Form a number pair , And from  nums  Remove ,nums = [] .
 Cannot form more pairs . A total of  1  Pairs of numbers ,nums  The rest of the world is  0  A digital .

 Example  3：
 Input ：nums = [0]
 Output ：[0,1]
 explain ： Cannot form a number of pairs ,nums  The rest of the world is  1  A digital .
 
 Tips ：
1 <= nums.length <= 100
0 <= nums[i] <= 100

source ： Power button （LeetCode）
link ：https://leetcode.cn/problems/maximum-number-of-pairs-in-array
Copyright belongs to the network . For commercial reprint, please contact the official authority , Non-commercial reprint please indicate the source .

2. Problem solving

• Counter Count , Take out the number and divide it 2

from collections import Counter
class Solution:
    def numberOfPairs(self, nums: List[int]) -> List[int]:
        c = Counter(nums).values()
        ct = sum([x//2 for x in c])
        return [ct, len(nums)-ct*2]

28 ms 15 MB Python3

---

my CSDN Blog address https://michael.blog.csdn.net/

Long click or sweep code pay attention to my official account （Michael amin ）, Come on together 、 Learn together ！