与排序算法不同,搜索算法是比较统一的,常用的搜索除hash外仅有两种,包括不需要排序的线性搜索和需要排序的binary search. 首先介绍一下binary search,其原理很直接,不断地选取有序数组的组中值,比较组中值与目标的大小,继续搜索目标所在的一半,直到找到目标,递归算法可以很直观的表现这个描述: int binarySearchRecursive(int A[], int low, int high, int key) { ; ; , key); , high, key); e…

public static int rank(int[] array, int k, int front, int rear) { if(front > rear) return -1; int mid = front + (rear - front) / 2; if(k == array[mid]) return mid; else if(k > array[mid]) return rank(array, k, mid + 1, rear); else return rank(array,…

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…

1 什么是trie trie是一棵多叉树,假如存放的是由26个字母(不区分大小写)构成的字符串的话,那么就是一棵26叉树. trie树是一棵前缀树,因为每个结点只保存字符串中的一个字符,整个字符串保存在路径中. trie树的根结点里面不保存任何字符,因为根结点是下面所有路径的前缀,如果固定为一个字符的话,那么该trie树只能保存以该字符为前缀的字符串了. trie树的每个结点要保存两类数据,一个是字符(root结点不保存),一个是到该字符所有后缀的结点的指针,比如26个字母的话,就是到该字符所有…

在sap 之abap语言中,有‍BINARY SEARCH这个查找条件.使用read table 来读取内表时,使用‍BINARY SEARCH可以大大的提高查找的效率,为什么呢?学过数据库的人会知道,"二分查找"法,其实这个‍BINARY SEARCH就是这样方法来查找的.书中也许会说,在使用‍BINARY SEARCH时,必须要先对内表排序,道理就是这样,因为我们知道,使用二分查找,一定要先排序,原因就是这些了. 在此说一下"二分查找".(因为书上没讲,我就把自…

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 thanthe node's key. The right subtree of a node contains only nodes with keys …

144. Binary Tree Preorder Traversal 前序的非递归遍历:用堆来实现 如果把这个代码改成先向堆存储左节点再存储右节点,就变成了每一行从右向左打印 如果用队列替代堆,并且先存储左节点,再存储右节点,就变成了逐行打印 class Solution { public: vector<int> preorderTraversal(TreeNode* root) { vector<int> result; if(root == NULL) return res…

Binary Search 有时候我们也把它叫做二进制查找 是一种较为高效的再数组中查找目标元素的方法 我们可以通过递归和非递归两种方式来实现它 //非递归 public static int binarySearch(int[] arr, int x) { int low = 0; int high = arr.length-1; while(low <= high) { int middle = (low + high)/2; if(x == arr[middle]) { return mi…

题目描述: Given a binary search tree (BST), find the lowest common ancestor (LCA) of two given nodes in the BST. According to the definition of LCA on Wikipedia: “The lowest common ancestor is defined between two nodes v and w as the lowest node in T tha…

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.…