peak-index-in-a-mountain-array

java

python

python3

mysql

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oraclesql

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javascript

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Algorithms

You are given an integer mountain array <code>arr</code> of length <code>n</code> where the values increase to a peak element and then decrease.

Return the index of the peak element.

Your task is to solve it in <code>O(log(n))</code> time complexity.

&nbsp;
Example 1:

<div class="example-block">
Input: arr = [0,1,0]

Output: 1
</div>

Example 2:

<div class="example-block">
Input: arr = [0,2,1,0]

Output: 1
</div>

Example 3:

<div class="example-block">
Input: arr = [0,10,5,2]

Output: 1
</div>

&nbsp;
Constraints:

<ul>
	<li><code>3 &lt;= arr.length &lt;= 105</code></li>
	<li><code>0 &lt;= arr[i] &lt;= 106</code></li>
	<li><code>arr</code> is guaranteed to be a mountain array.</li>
</ul>

peakIndexInMountainArray

Peak Index in a Mountain Array

Find Peak Element

find-peak-element

寻找峰值

Find in Mountain Array

find-in-mountain-array

山脉数组中查找目标值

Minimum Number of Removals to Make Mountain Array

minimum-number-of-removals-to-make-mountain-array

得到山形数组的最少删除次数

Array

Binary Search

给定一个长度为&nbsp;<code>n</code>&nbsp;的整数 山脉&nbsp;数组&nbsp;<code>arr</code>&nbsp;，其中的值递增到一个&nbsp;峰值元素&nbsp;然后递减。

返回峰值元素的下标。

你必须设计并实现时间复杂度为 <code>O(log(n))</code> 的解决方案。

&nbsp;

示例 1：

<pre>
输入：arr = [0,1,0]
输出：1
</pre>

示例 2：

<pre>
输入：arr = [0,2,1,0]
输出：1
</pre>

示例 3：

<pre>
输入：arr = [0,10,5,2]
输出：1
</pre>

&nbsp;

提示：

<ul>
	<li><code>3 &lt;= arr.length &lt;= 105</code></li>
	<li><code>0 &lt;= arr[i] &lt;= 106</code></li>
	<li>题目数据 保证 <code>arr</code> 是一个山脉数组</li>
</ul>