Given a collection of candidate numbers (C) and a target number (T), find all unique combinations in C where the candidate numbers sums to T. Each number in C may only be used once in the combination. Note: All numbers (including target) will be posi…

Write a program to solve a Sudoku puzzle by filling the empty cells. Empty cells are indicated by the character '.'. You may assume that there will be only one unique solution. A sudoku puzzle... ...and its solution numbers marked in red. 题意分析: 本题是要解…

Given a sorted array and a target value, return the index if the target is found. If not, return the index where it would be if it were inserted in order. You may assume no duplicates in the array. Here are few examples.[1,3,5,6], 5 → 2[1,3,5,6], 2 →…

算法和数据结构知识点图 首先,了解算法和数据结构有哪些知识点,在后面的学习中有 大局观,对学习和刷题十分有帮助. 下面是我花了一天时间花的算法和数据结构的知识结构,大家可以看看. 后面是为大家 精心挑选的LeetCode题单,并根据题目知识点的类型分好了类别,大家可以根据每个知识点,进行有针对性的刷题. 数据结构 数组&双指针 LeetCode 1. 两数之和 LeetCode 4. 寻找两个正序数组的中位数 LeetCode 15. 三数之和 LeetCode 75. 颜色分类 LeetCod…

Given an array where elements are sorted in ascending order, convert it to a height balanced BST. 题解:递归就可以了. Java代码如下: /** * Definition for binary tree * public class TreeNode { * int val; * TreeNode left; * TreeNode right; * TreeNode(int x) { val =…

Given a singly linked list where elements are sorted in ascending order, convert it to a height balanced BST. 题解:开始想到的方法比较偷懒,直接遍历一遍数组,把每个ListNode对应的值放到数组里面,然后把数组转换成BST,想来这个题的本意肯定不是这样. 自己也想到了bottom-up的方法,但是没想明白怎么个bottom-up法,真的是昨天做梦都在想=.= 今天早上终于弄懂了,用递归…

Given two binary trees, write a function to check if they are equal or not. Two binary trees are considered equal if they are structurally identical and the nodes have the same value. 解题:还是简单的递归,把情况考虑清楚就可以了: 根节点都为空,树相同: 根节点一方为空,另一方不为空,树不相同: 根节点值不想等,树…

Given a binary tree, return the level order traversal of its nodes' values. (ie, from left to right, level by level). For example:Given binary tree {3,9,20,#,#,15,7}, / \ / \ return its level order traversal as: [ [], [,], [,] ] 题解:二叉树的层次遍历,用队列实现.重点在…

Given a binary tree, return the inorder traversal of its nodes' values. For example:Given binary tree {1,#,2,3}, 1 \ 2 / 3 return [1,3,2]. Note: Recursive solution is trivial, could you do it iteratively? 解题:果然不能晚上做题,效率好低.看了讨论才学会的解法.设置一个指针next指向当前访问的…

Given a binary tree, return the preorder traversal of its nodes' values. For example:Given binary tree {1,#,2,3}, 1 \ 2 / 3 return [1,2,3]. Note: Recursive solution is trivial, could you do it iteratively? 解题:应该是很简单的一道题,纠结了好久T_T 基本思路很简单,用栈模拟就可以了.首先根节…