number-of-smooth-descent-periods-of-a-stock

java

python

python3

mysql

mssql

oraclesql

csharp

javascript

typescript

bash

swift

kotlin

dart

golang

ruby

scala

rust

racket

erlang

elixir

pythondata

postgresql

cangjie

Algorithms

You are given an integer array <code>prices</code> representing the daily price history of a stock, where <code>prices[i]</code> is the stock price on the <code>ith</code> day.

A smooth descent period of a stock consists of one or more contiguous days such that the price on each day is lower than the price on the preceding day by exactly <code>1</code>. The first day of the period is exempted from this rule.

Return the number of smooth descent periods.

&nbsp;
Example 1:

<pre>
Input: prices = [3,2,1,4]
Output: 7
Explanation: There are 7 smooth descent periods:
[3], [2], [1], [4], [3,2], [2,1], and [3,2,1]
Note that a period with one day is a smooth descent period by the definition.
</pre>

Example 2:

<pre>
Input: prices = [8,6,7,7]
Output: 4
Explanation: There are 4 smooth descent periods: [8], [6], [7], and [7]
Note that [8,6] is not a smooth descent period as 8 - 6 &ne; 1.
</pre>

Example 3:

<pre>
Input: prices = [1]
Output: 1
Explanation: There is 1 smooth descent period: [1]
</pre>

&nbsp;
Constraints:

<ul>
	<li><code>1 &lt;= prices.length &lt;= 105</code></li>
	<li><code>1 &lt;= prices[i] &lt;= 105</code></li>
</ul>

getDescentPeriods

Number of Smooth Descent Periods of a Stock

Subarray Product Less Than K

subarray-product-less-than-k

乘积小于 K 的子数组

Number of Valid Subarrays

number-of-valid-subarrays

有效子数组的数目

Number of Zero-Filled Subarrays

number-of-zero-filled-subarrays

全 0 子数组的数目

Array

Math

Dynamic Programming

给你一个整数数组&nbsp;<code>prices</code>&nbsp;，表示一支股票的历史每日股价，其中&nbsp;<code>prices[i]</code>&nbsp;是这支股票第&nbsp;<code>i</code>&nbsp;天的价格。

一个 平滑下降的阶段&nbsp;定义为：对于&nbsp;连续一天或者多天&nbsp;，每日股价都比 前一日股价恰好少 <code>1</code>&nbsp;，这个阶段第一天的股价没有限制。

请你返回 平滑下降阶段&nbsp;的数目。

&nbsp;

示例 1：

<pre>输入：prices = [3,2,1,4]
输出：7
解释：总共有 7 个平滑下降阶段：
[3], [2], [1], [4], [3,2], [2,1] 和 [3,2,1]
注意，仅一天按照定义也是平滑下降阶段。
</pre>

示例 2：

<pre>输入：prices = [8,6,7,7]
输出：4
解释：总共有 4 个连续平滑下降阶段：[8], [6], [7] 和 [7]
由于 8 - 6 ≠ 1 ，所以 [8,6] 不是平滑下降阶段。
</pre>

示例 3：

<pre>输入：prices = [1]
输出：1
解释：总共有 1 个平滑下降阶段：[1]
</pre>

&nbsp;

提示：

<ul>
	<li><code>1 &lt;= prices.length &lt;= 105</code></li>
	<li><code>1 &lt;= prices[i] &lt;= 105</code></li>
</ul>