LeetCode contest 200 5475. 统计好三元组 Count Good Triplets
Table of Contents
一、中文版
给你一个整数数组 arr ，以及 a、b 、c 三个整数。请你统计其中好三元组的数量。
如果三元组 (arr[i], arr[j], arr[k]) 满足下列全部条件，则认为它是一个 好三元组 。
0 <= i < j < k < arr.length
|arr[i] - arr[j]| <= a
|arr[j] - arr[k]| <= b
|arr[i] - arr[k]| <= c
其中 |x| 表示 x 的绝对值。
返回 好三元组的数量 。
示例 1：
输入：arr = [3,0,1,1,9,7], a = 7, b = 2, c = 3
输出：4
解释：一共有 4 个好三元组：[(3,0,1), (3,0,1), (3,1,1), (0,1,1)] 。
示例 2：
输入：arr = [1,1,2,2,3], a = 0, b = 0, c = 1
输出：0
解释：不存在满足所有条件的三元组。
提示：
3 <= arr.length <= 100
0 <= arr[i] <= 1000
0 <= a, b, c <= 1000
二、英文版
Given an array of integers arr, and three integers a, b and c. You need to find the number of good triplets. A triplet (arr[i], arr[j], arr[k]) is good if the following conditions are true: 0 <= i < j < k < arr.length |arr[i] - arr[j]| <= a |arr[j] - arr[k]| <= b |arr[i] - arr[k]| <= c Where |x| denotes the absolute value of x. Return the number of good triplets. Example 1: Input: arr = [3,0,1,1,9,7], a = 7, b = 2, c = 3 Output: 4 Explanation: There are 4 good triplets: [(3,0,1), (3,0,1), (3,1,1), (0,1,1)]. Example 2: Input: arr = [1,1,2,2,3], a = 0, b = 0, c = 1 Output: 0 Explanation: No triplet satisfies all conditions. Constraints: 3 <= arr.length <= 100 0 <= arr[i] <= 1000 0 <= a, b, c <= 1000
三、My answer
class Solution: def countGoodTriplets(self, arr: List[int], a: int, b: int, c: int) -> int: res = 0 n = len(arr) for i in range(n): for j in range(i+1,n): for k in range(j+1,n): if abs(arr[i]-arr[j]) <= a and abs(arr[j] - arr[k]) <= b and abs(arr[i] -arr[k]) <= c: res += 1 return res
四、解题报告
数据结构：数组
算法：遍历
实现：按照题意描述遍历即可
