852. Peak Index in a Mountain Array -- Easy 方法一:二分查找 int peakIndexInMountainArray(vector<int>& A) { // insert another two elements to avoid out of bound const int INT_MAX_ = 2147483647; const int INT_MIN_ = (-INT_MAX_-1); // insert INT_MIN_ befo…

problem 852. Peak Index in a Mountain Array solution1: class Solution { public: int peakIndexInMountainArray(vector<int>& A) { return max_element(A.begin(), A.end())-A.begin(); } }; solution2: class Solution { public: int peakIndexInMountainArra…

作者: 负雪明烛 id: fuxuemingzhu 个人博客: http://fuxuemingzhu.cn/ 目录 题目描述 题目大意 解题方法 二分查找 查找最大值位置 寻找第一个下降的位置 日期 题目地址:https://leetcode.com/problems/peak-index-in-a-mountain-array/description/ 题目描述 Let's call an array A a mountain if the following properties hold…

题目要求 Let's call an array A a mountain if the following properties hold: A.length >= 3 There exists some 0 < i < A.length - 1 such that A[0] < A[1] < ... A[i-1] < A[i] > A[i+1] > ... > A[A.length - 1] Given an array that is defin…

Let's call an array A a mountain if the following properties hold: A.length >= 3 There exists some 0 < i < A.length - 1 such that A[0] < A[1] < ... A[i-1] < A[i] > A[i+1] > ... > A[A.length - 1] Given an array that is definitely…

题目标签:Binary Search 题目给了我们一组 int array,让我们找到数组的 peak. 利用 binary search, 如果数字比它后面那个数字小,说明还在上坡,缩小范围到右半边: 如果一个数字比它后面的大,说明是下坡,或者是peak,缩小范围到左半边,这里要包含mid,因为mid 可能是peak.具体看code. Java Solution: Runtime:  0 ms, faster than 100 % Memory Usage: 39 MB, less than…

Input: [0,1,0] Output: 1 Input: [0,2,1,0] Output: 1解: 比较数组中的i和i-1的大小,如果前一位大于后一位数字,前一位则是结果 let ans = 0; for(let i = 0;i<A.length; i++){ if(A[i] < A[i-1]){ ans = i-1; break; } } return ans;…

class Solution { public: int peakIndexInMountainArray(vector<int>& A) { return max_element(A.begin(),A.end())-A.begin(); } }; 这题很简单,问题不大.…

Leetcode之二分法专题-852. 山脉数组的峰顶索引(Peak Index in a Mountain Array) 我们把符合下列属性的数组 A 称作山脉: A.length >= 3 存在 0 < i < A.length - 1 使得A[0] < A[1] < ... A[i-1] < A[i] > A[i+1] > ... > A[A.length - 1] 给定一个确定为山脉的数组,返回任何满足 A[0] < A[1] <…

Let's call an array A a mountain if the following properties hold: A.length >= 3 There exists some 0 < i < A.length - 1 such that A[0] < A[1] < ... A[i-1] < A[i] > A[i+1] > ... > A[A.length - 1] Given an array that is definitely…

Let's call an array A a mountain if the following properties hold: A.length >= 3 There exists some 0 < i < A.length - 1 such that A[0] < A[1] < ... A[i-1] < A[i] > A[i+1] > ... > A[A.length - 1] Given an array that is definitely…

问题 该文章的最新版本已迁移至个人博客[比特飞],单击链接 https://www.byteflying.com/archives/4003 访问. 我们把符合下列属性的数组 A 称作山脉: A.length >= 3 存在 0 < i < A.length - 1 使得A[0] < A[1] < ... A[i-1] < A[i] > A[i+1] > ... > A[A.length - 1] 给定一个确定为山脉的数组,返回任何满足 A[0] &l…

这是悦乐书的第329次更新,第352篇原创 01 看题和准备 今天介绍的是LeetCode算法题中Easy级别的第199题(顺位题号是852).如果以下属性成立,我们将数组A称为山: A.length> = 3. 存在一个i(0 < i < A.length-1),使得A[0] <A[1] <... A[i-1] < A[i] > A[i + 1]> ...> A[A.length - 1]. 给定一个绝对是山的数组,返回i,使得A[0] <A[…

Given an array A of integers, return true if and only if it is a valid mountain array. Recall that A is a mountain array if and only if: A.length >= 3 There exists some i with 0 < i < A.length - 1 such that: A[0] < A[1] < ... A[i-1] < A[…

Given an array A of integers, return true if and only if it is a valid mountain array. Recall that A is a mountain array if and only if: A.length >= 3 There exists some i with 0 < i < A.length - 1 such that: A[0] < A[1] < ... A[i-1] < A[…

题目如下: (This problem is an interactive problem.) You may recall that an array A is a mountain array if and only if: A.length >= 3 There exists some i with 0 < i < A.length - 1 such that: A[0] < A[1] < ... A[i-1] < A[i] A[i] > A[i+1] &g…

Given an array A of integers, return true if and only if it is a valid mountain array. Recall that A is a mountain array if and only if: A.length >= 3 There exists some i with 0 < i < A.length - 1 such that: A[0] < A[1] < ... A[i-1] < A[…

problem 941. Valid Mountain Array solution: class Solution { public: bool validMountainArray(vector<int>& A) { ) return false; ], max_id = ; ; i<A.size(); ++i) { if(A[i]>max) { max = A[i]; max_id = i; } } || max_id==A.size()-) return false…

941. 有效的山脉数组 941. Valid Mountain Array 题目描述 给定一个整数数组 A,如果它是有效的山脉数组就返回 true,否则返回 false. 让我们回顾一下,如果 A 满足下述条件,那么它是一个山脉数组: A.length >= 3 在 0 < i < A.length - 1 条件下,存在 i 使得: A[0] < A[1] < ... A[i-1] < A[i] A[i] > A[i+1] > ... > A[B.l…

题目如下: Given an array A of integers, return true if and only if it is a valid mountain array. Recall that A is a mountain array if and only if: A.length >= 3 There exists some i with 0 < i < A.length - 1 such that: A[0] < A[1] < ... A[i-1] &…

作者: 负雪明烛 id: fuxuemingzhu 个人博客: http://fuxuemingzhu.cn/ 目录 题目描述 题目大意 解题方法 日期 题目地址:https://leetcode.com/problems/valid-mountain-array/description/ 题目描述 Given an array A of integers, return true if and only if it is a valid mountain array. Recall that…

作者: 负雪明烛 id: fuxuemingzhu 个人博客:http://fuxuemingzhu.cn/ 目录 题目描述 题目大意 解题方法 二分查找 日期 题目地址:https://leetcode-cn.com/problems/find-in-mountain-array/ 题目描述 给你一个 山脉数组 mountainArr,请你返回能够使得 mountainArr.get(index) 等于 target 最小 的下标 index 值. 如果不存在这样的下标 index,就请返回…

题目标签:Array 题目给了一组int array A,让我们判断它是否是 一个山脉数组. 山脉数组一定要有一个最高值,然后要同时有 山坡和下坡. 想法是,从左边开始依次比较两个数字,int[0] int[1].... 如果是上坡,继续寻找,如果遇到了下坡,停止,这样就找到了最高点. 从右边也是同样的操作. 然后排除只有上坡的,或者只有下坡的情况. 最后比较一下, 左边找到的最高点和右边找到的最高点是否是同一个点. 具体看code. Java Solution: Runtime beats 9…

这是悦乐书的第360次更新,第387篇原创 01 看题和准备 今天介绍的是LeetCode算法题中Easy级别的第222题(顺位题号是941).给定一个整数数组A,当且仅当它是一个有效的山形数组时返回true. A是一个山形数组,当且仅当: A.length> = 3 存在一些具有0 < i < A.length-1的i,使得: A[0] < A[1] < ... < A[i-1] < A[i] A[i] > A[i+1] > ... > A[A…

1 题目描述 2.问题分析 直接从后向前遍历,找到 A[i] > A[i-1] 即可. 3.代码 int peakIndexInMountainArray(vector<int>& A) { ; ){ ]){ return i; } i--; } }…

Binary Search 二分法方法总结 code教你做人:二分法核心思想是把一个大的问题拆成若干个小问题,最重要的是去掉一半或者选择一半. 二分法模板: public int BinarySearchTemplate(int[] nums,int target) { if(nums == null || nums.length == 0) return -1; int lo = 0; int hi = nums.length - 1; //A: lo < hi [1,2]找1 找last p…

Binary Search T(n) = T(n/2) + O(1)   =>    T(n) = O(lg n) proof: 如果能用iterable , 就用while loop, 可以防止用recursion的时候stack overflow( process in Linux is 8Mb), stack room is static for each process. (堆空间, heap room 是内存, 是动态的.)层数越多,存储更多中间/临时变量,最终超过系统配的stack空…

All LeetCode Questions List(Part of Answers, still updating) 题目汇总及部分答案(持续更新中) Leetcode problems classified by company 题目按公司分类(Last updated: October 2, 2017) .   Top Interview Questions # Title Difficulty Acceptance 1 Two Sum Medium 17.70% 2 Add Two N…

二分法模板 非递归版本: public class Solution { /** * @param A an integer array sorted in ascending order * @param target an integer * @return an integer */ public int findPosition(int[] nums, int target) { if (nums == null || nums.length == 0) { return -1; } i…

A peak element is an element that is greater than its neighbors. Given an input array where num[i] ≠ num[i+1], find a peak element and return its index. The array may contain multiple peaks, in that case return the index to any one of the peaks is fi…