Package g2101_2200.s2179_count_good_triplets_in_an_array

Class Solution

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public final class Solution

    2179 - Count Good Triplets in an Array.

    Hard

    You are given two 0-indexed arrays nums1 and nums2 of length n, both of which are permutations of [0, 1, ..., n - 1].

    A good triplet is a set of 3 distinct values which are present in increasing order by position both in nums1 and nums2. In other words, if we consider <code>pos1<sub>v</sub></code> as the index of the value v in nums1 and <code>pos2<sub>v</sub></code> as the index of the value v in nums2, then a good triplet will be a set (x, y, z) where 0 &lt;= x, y, z &lt;= n - 1, such that <code>pos1<sub>x</sub>< pos1<sub>y</sub>< pos1<sub>z</sub></code> and <code>pos2<sub>x</sub>< pos2<sub>y</sub>< pos2<sub>z</sub></code>.

    Return the total number of good triplets.

    Example 1:

    Input: nums1 = 2,0,1,3, nums2 = 0,1,2,3

    Output: 1

    Explanation:

    There are 4 triplets (x,y,z) such that pos1<sub>x</sub>< pos1<sub>y</sub>< pos1<sub>z</sub>. They are (2,0,1), (2,0,3), (2,1,3), and (0,1,3).

    Out of those triplets, only the triplet (0,1,3) satisfies pos2<sub>x</sub>< pos2<sub>y</sub>< pos2<sub>z</sub>.

    Hence, there is only 1 good triplet.

    Example 2:

    Input: nums1 = 4,0,1,3,2, nums2 = 4,1,0,2,3

    Output: 4

    Explanation: The 4 good triplets are (4,0,3), (4,0,2), (4,1,3), and (4,1,2).

    Constraints:

    • n == nums1.length == nums2.length

    • <code>3 <= n <= 10<sup>5</sup></code>

    • 0 &lt;= nums1[i], nums2[i] &lt;= n - 1

    • nums1 and nums2 are permutations of [0, 1, ..., n - 1].

    • Nested Class Summary

      Nested Classes 
      Modifier and Type Class Description

    • Field Summary

      Fields 
      Modifier and Type Field Description

    • Constructor Summary

      Constructors 
      Constructor Description
      Solution()

    • Enum Constant Summary

      Enum Constants 
      Enum Constant Description

    • Method Summary

      Modifier and Type Method Description
      final Long goodTriplets(IntArray nums1, IntArray nums2)

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait