Hash2367. Number of Arithmetic Triplets

Solved

Easy

Topics

Companies

Hint

You are given a 0-indexed, strictly increasing integer array nums and a positive integer diff. A triplet (i, j, k) is an arithmetic triplet if the following conditions are met:

• i < j < k,
• nums[j] - nums[i] == diff, and
• nums[k] - nums[j] == diff.

Return the number of unique arithmetic triplets.

Example 1:

Input: nums = [0,1,4,6,7,10], diff = 3
Output: 2
Explanation:
(1, 2, 4) is an arithmetic triplet because both 7 - 4 == 3 and 4 - 1 == 3.
(2, 4, 5) is an arithmetic triplet because both 10 - 7 == 3 and 7 - 4 == 3.

Example 2:

Input: nums = [4,5,6,7,8,9], diff = 2
Output: 2
Explanation:
(0, 2, 4) is an arithmetic triplet because both 8 - 6 == 2 and 6 - 4 == 2.
(1, 3, 5) is an arithmetic triplet because both 9 - 7 == 2 and 7 - 5 == 2.

Constraints:

• 3 <= nums.length <= 200
• 0 <= nums[i] <= 200
• 1 <= diff <= 50
• nums is strictly increasing.

class Solution {

    /**
    Time : O(n^3)
    Space :O(n)
     */
    public int arithmeticTriplets(int[] nums, int diff) {
        
        int n=nums.length;
        Set<String> hSet=new HashSet<>();

        for(int i=0;i<n-2;i++){
            for(int j=i+1;j<n-1;j++){
                for(int k=j+1;k<n;k++){
                    if((nums[j]-nums[i]==diff) && (nums[k]-nums[j] == diff)) hSet.add( i+","+j+","+k);
                }
            }
        }
        // System.out.println(hSet);
        return hSet.size();
        
    }
}

/**
2367. Number of Arithmetic Triplets
Solved
Easy
Topics
Companies
Hint
You are given a 0-indexed, strictly increasing integer array nums and a positive integer diff. A triplet (i, j, k) is an arithmetic triplet if the following conditions are met:

i < j < k,
nums[j] - nums[i] == diff, and
nums[k] - nums[j] == diff.
Return the number of unique arithmetic triplets.

 

Example 1:

Input: nums = [0,1,4,6,7,10], diff = 3
Output: 2
Explanation:
(1, 2, 4) is an arithmetic triplet because both 7 - 4 == 3 and 4 - 1 == 3.
(2, 4, 5) is an arithmetic triplet because both 10 - 7 == 3 and 7 - 4 == 3. 
Example 2:

Input: nums = [4,5,6,7,8,9], diff = 2
Output: 2
Explanation:
(0, 2, 4) is an arithmetic triplet because both 8 - 6 == 2 and 6 - 4 == 2.
(1, 3, 5) is an arithmetic triplet because both 9 - 7 == 2 and 7 - 5 == 2.

Constraints:

3 <= nums.length <= 200
0 <= nums[i] <= 200
1 <= diff <= 50
nums is strictly increasing.
 */