## DEV Community

Abhishek Chaudhary

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# Count Good Triplets

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:

``````class Solution:
def countGoodTriplets(self, arr: List[int], a: int, b: int, c: int) -> int:
n = len(arr)
ctr = 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:
ctr += 1
return ctr
``````