Leetcode 1814. Count Nice Pairs in an Array

Posted 2021-08-21 SnailTyan

文章作者：Tyan
博客：noahsnail.com  |  CSDN  |  简书

1. Description

2. Solution

**解析：**Version 1，由题目可知nums[i] - rev(nums[i])相等的两个数即可构成一个合适的对，因此统计nums[i] - rev(nums[i])相等的数值即可。

• Version 1

class Solution:
    def countNicePairs(self, nums: List[int]) -> int:
        count = 0
        n = len(nums)
        stat = {}
        MODULE = 10**9 + 7
        for i in range(n):
            diff = nums[i] - int(str(nums[i])[::-1])
            stat[diff] = stat.get(diff, 0) + 1
            if stat[diff] > 1:
                count += stat[diff] - 1
        return count % MODULE

Reference

1. https://leetcode.com/problems/count-nice-pairs-in-an-array/