leetcode-1534-easy

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.

思路一：刚开始想有没有简化的解法，没想到，就直接用暴力解法了，直接遍历所有可能性

public int countGoodTriplets(int[] arr, int a, int b, int c) {
    int result = 0;
    for (int i = 0; i < arr.length; i++) {
        for (int j = i + 1; j < arr.length; j++) {
            for (int k = j + 1; k < arr.length; k++) {

                if (Math.abs(arr[i] - arr[j]) <= a &&
                        Math.abs(arr[j] - arr[k]) <= b &&
                        Math.abs(arr[i] - arr[k]) <= c) {
                    result++;
                }
            }
        }
    }

    return result;
}