Construct binary tree from preorder and inorder traversal 题目描述 Given preorder and inorder traversal of a tree, construct the binary tree. Note:  You may assume that duplicates do not exist in the tree. 思路 关于根据前序和中序如何得到二叉树的结构的计算方式，我就不重复了，之前的程序里面也有，这里就只说说代码里几个参数…

valid sudoku 题目描述 Determine if a Sudoku is valid, according to: Sudoku Puzzles - The Rules.The Sudoku board could be partially filled, where empty cells are filled with the character'.'. 题目解析 数独具有以下规则： 每一行所有元素不能重复（1~9）； 每一列所有元素不能重复（1~9）； 由第3i~3(i)+2行和第3i~3(i)+…

Search for a range 题目描述 Given a sorted array of integers, find the starting and ending position of a given target value.Your algorithm's runtime complexity must be in the order of O(log n).If the target is not found in the array, return[-1, -1].For example, Gi…

Remove Duplicates from sorted Array II 题目描述 Follow up for "Remove Duplicates": What if duplicates are allowed at most twice?For example, Given sorted array A =[1,1,1,2,2,3],Your function should return length =5, and A is now[1,1,2,2,3]. 题目解析 类似于Remove Duplicat…

Remove duplicates from sorted list 题目描述 Given a sorted linked list, delete all duplicates such that each element appear only once.For example, Given1->1->2, return1->2. Given1->1->2->3->3, return1->2->3.（保留1个） 题目解析 对于当前节点和下一节点的值不相等的情况，那就一直往下走，代码中是p1移动到下一个节点的操作…

unique path 题目描述 A robot is located at the top-left corner of a m x n grid (marked 'Start' in the diagram below).The robot can only move either down or right at any point in time. The robot is trying to reach the bottom-right corner of the grid (marked 'Finish…

merge sorted array 题目描述 Given two sorted integer arrays A and B, merge B into A as one sorted array.Note:  You may assume that A has enough space to hold additional elements from B. The number of elements initialized in A and B are mand n respectively. 题目解析 由于…