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1534. Count Good Triplets

Difficulty Topics

Description

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

Solution

count-good-triplets.py
class Solution:
    def countGoodTriplets(self, arr: List[int], a: int, b: int, c: int) -> int:
        n = len(arr)

        res = 0
        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
count-good-triplets.cpp
class Solution {
public:
    int countGoodTriplets(vector<int>& arr, int a, int b, int c) {
        int n = arr.size();
        int ans = 0;
        for (int i=0; i < n; ++i){
            for (int j = i+1; j < n; ++j){
                for (int k=j+1; k<n; ++k){
                    ans += abs(arr[i]-arr[j])<=a && abs(arr[j]-arr[k])<=b && abs(arr[i]-arr[k])<=c;
                }
            }
        }

        return ans;
    }
};