704. Binary Search 1.使用start+1 < end,这样保证最后剩两个数 2.mid = start + (end - start)/2,这样避免接近max-int导致的溢出 3.start.end直接等于mid 4.最后比较两个位置 class Solution { public: int search(vector<int>& nums, int target) { if(nums.empty()) ; ; ; int mid; < end){ m…

题目标签:Binary Search 很标准的一个二分查找,具体看code. Java Solution: Runtime:  0 ms, faster than 100 % Memory Usage: 39 MB, less than 90 % 完成日期:07/31/2019 关键点:二分查找 class Solution { public int search(int[] nums, int target) { int left = 0; int right = nums.length -…

Description Given a sorted (in ascending order) integer array nums of n elements and a target value, write a function to search target in nums. If target exists, then return its index, otherwise return -1. Example 1: Input: nums = [-1,0,3,5,9,12], ta…

这4个题都是针对旋转的排序数组.其中153.154是在旋转的排序数组中找最小值,33.81是在旋转的排序数组中找一个固定的值.且153和33都是没有重复数值的数组,154.81都是针对各自问题的版本1增加了有重复数值的限制条件. 153.154都需要考虑是否旋转成和原数组一样的情况,特别的,154题还需要考虑10111和11101这种特殊情况无法使用二分查找. 33.81则不用考虑这些情况. 找最小值的题主要是利用最小值小于他前一个位置的数,同时也小于后一个位置的数 153. Find Mini…

LeetCode:Unique Binary Search Trees Given n, how many structurally unique BST's (binary search trees) that store values 1...n? For example,Given n = 3, there are a total of 5 unique BST's. 1 3 3 2 1 \ / / / \ \ 3 2 1 1 3 2 / / \ \ 2 1 2 3 分析:依次把每个节点作…

LeetCode: Validata Binary Search Tree Given a binary tree, determine if it is a valid binary search tree (BST). Assume a BST is defined as follows: The left subtree of a node contains only nodes with keys less than the node's key. The right subtree o…

problem 704. Binary Search solution: class Solution { public: int search(vector<int>& nums, int target) { , right = nums.size()-, mid = ; while(left<=right)//errr... { mid = left + (right-left)/; ; ; else return mid; } ; } }; 参考 1. Leetcode_e…

Given a sorted (in ascending order) integer array nums of n elements and a target value, write a function to search target in nums. If target exists, then return its index, otherwise return -1. Example 1: Input: nums = [-1,0,3,5,9,12], target = 9 Out…

Given a non-empty binary search tree and a target value, find k values in the BST that are closest to the target. Note: Given target value is a floating point. You may assume k is always valid, that is: k ≤ total nodes. You are guaranteed to have onl…

Given a non-empty binary search tree and a target value, find the value in the BST that is closest to the target. Note: Given target value is a floating point. You are guaranteed to have only one unique value in the BST that is closest to the target.…

Two elements of a binary search tree (BST) are swapped by mistake. Recover the tree without changing its structure. Note:A solution using O(n) space is pretty straight forward. Could you devise a constant space solution? confused what "{1,#,2,3}"…

Given a binary tree, determine if it is a valid binary search tree (BST). Assume a BST is defined as follows: The left subtree of a node contains only nodes with keys less than the node's key. The right subtree of a node contains only nodes with keys…

Given n, how many structurally unique BST's (binary search trees) that store values 1...n? For example,Given n = 3, there are a total of 5 unique BST's. 1 3 3 2 1 \ / / / \ \ 3 2 1 1 3 2 / / \ \ 2 1 2 3 这道题实际上是Catalan Number卡塔兰数的一个例子,如果对卡塔兰数不熟悉的童鞋可能真…

Given n, generate all structurally unique BST's (binary search trees) that store values 1...n. For example,Given n = 3, your program should return all 5 unique BST's shown below. 1 3 3 2 1 \ / / / \ \ 3 2 1 1 3 2 / / \ \ 2 1 2 3 confused what "{1,#,2…

原题链接在这里:https://leetcode.com/problems/closest-binary-search-tree-value-ii/ 题目: Given a non-empty binary search tree and a target value, find k values in the BST that are closest to the target. Note: Given target value is a floating point. You may ass…

原题链接在这里:https://leetcode.com/problems/closest-binary-search-tree-value/ Given a non-empty binary search tree and a target value, find the value in the BST that is closest to the target. Note: Given target value is a floating point. You are guaranteed…

https://leetcode.com/problems/binary-search-tree-iterator/ Implement an iterator over a binary search tree (BST). Your iterator will be initialized with the root node of a BST. Calling next() will return the next smallest number in the BST. Note: nex…

原题地址:https://oj.leetcode.com/problems/unique-binary-search-trees/ 题意: Given n, how many structurally unique BST's (binary search trees) that store values 1...n? For example,Given n = 3, there are a total of 5 unique BST's. 1 3 3 2 1 \ / / / \ \ 3 2 1…

原题地址:https://oj.leetcode.com/problems/recover-binary-search-tree/ 题意: Two elements of a binary search tree (BST) are swapped by mistake. Recover the tree without changing its structure. 解题思路:这题是说一颗二叉查找树中的某两个节点被错误的交换了,需要恢复成原来的正确的二叉查找树. 算法一:思路很简单,一颗二叉查…

Implement an iterator over a binary search tree (BST). Your iterator will be initialized with the root node of a BST. Calling next() will return the next smallest number in the BST. Note: next() and hasNext() should run in average O(1) time and uses…

Given n, how many structurally unique BST's (binary search trees) that store values 1...n? For example,Given n = 3, there are a total of 5 unique BST's. 1 3 3 2 1 \ / / / \ \ 3 2 1 1 3 2 / / \ \ 2 1 2 3 Tree Dynamic Programming     如果集合为空,只有一种BST,即空树…

Implement an iterator over a binary search tree (BST). Your iterator will be initialized with the root node of a BST. Calling next() will return the next smallest number in the BST. Note: next() and hasNext() should run in average O(1) time and uses…

Implement an iterator over a binary search tree (BST). Your iterator will be initialized with the root node of a BST. Calling next() will return the next smallest number in the BST. Note: next() and hasNext() should run in average O(1) time and uses…

Given a binary tree, determine if it is a valid binary search tree (BST). Assume a BST is defined as follows: The left subtree of a node contains only nodes with keys less than the node's key. The right subtree of a node contains only nodes with keys…

Given n, how many structurally unique BST's (binary search trees) that store values 1...n? For example,Given n = 3, there are a total of 5 unique BST's. 1 3 3 2 1 \ / / / \ \ 3 2 1 1 3 2 / / \ \ 2 1 2 3 题目的的意思是给出n个节点,求出有多少不同的二叉树,实际是计算卡特兰数可以参考二叉树.卡特兰数…

Given a binary tree, determine if it is a valid binary search tree (BST). Assume a BST is defined as follows: The left subtree of a node contains only nodes with keys less than the node's key. The right subtree of a node contains only nodes with keys…

Two elements of a binary search tree (BST) are swapped by mistake. Recover the tree without changing its structure. Note:A solution using O(n) space is pretty straight forward. Could you devise a constant space solution? confused what "{1,#,2,3}"…

Unique Binary Search Trees II Given n, generate all structurally unique BST's (binary search trees) that store values 1...n. For example, Given n = 3, your program should return all 5 unique BST's shown below. 1         3     3      2      1 \      …

题目: Given n, generate all structurally unique BST's (binary search trees) that store values 1...n. For example, Given n = 3, your program should return all 5 unique BST's shown below. 1 3 3 2 1 \ / / / \ \ 3 2 1 1 3 2 / / \ \ 2 1 2 3 思路: 仍和Unique Bin…

Binary Search Tree Iterator Implement an iterator over a binary search tree (BST). Your iterator will be initialized with the root node of a BST. Calling next() will return the next smallest number in the BST. Note: next() and hasNext() should run in…