1512_number_of_good_pairs.py

class Solution:
    def numIdenticalPairs(self, nums: List[int]) -> int:
        
        def cal_same_num_pairs(n: int) -> int:
            if n < 2:
                return 0
            else:
                ans = 1
                for i in range(2, n):
                    ans += i
                return ans

        num_dict = {}
        for num in nums:
            if num not in num_dict:
                num_dict[num] = 1
            else:
                num_dict[num] += 1
        ans = 0
        for num in num_dict.keys():
            ans += cal_same_num_pairs(num_dict[num])
        return ans

'''
    This is my personal record of solving Leetcode Problems. 
    If you have any questions, please discuss them in [Issues](https://github.com/mengxinayan/leetcode/issues).
    Copyright (C) 2020-2022  mengxinayan

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
'''