673\. Number of Longest Increasing Subsequence

Medium

Given an integer array `nums`, return _the number of longest increasing subsequences._

**Notice** that the sequence has to be **strictly** increasing.

**Example 1:**

**Input:** nums = [1,3,5,4,7]

**Output:** 2

**Explanation:** The two longest increasing subsequences are [1, 3, 4, 7] and [1, 3, 5, 7].

**Example 2:**

**Input:** nums = [2,2,2,2,2]

**Output:** 5

**Explanation:** The length of longest continuous increasing subsequence is 1, and there are 5 subsequences' length is 1, so output 5.

**Constraints:**

*   `1 <= nums.length <= 2000`
*   <code>-10<sup>6</sup> <= nums[i] <= 10<sup>6</sup></code>