引用自 http://blog.csdn.net/wangxiaojun911/article/details/18922337,此处仅作为自己参考 1.Two SUM Given an array of integers, return indices of the two numbers such that they add up to a specific target. You may assume that each input would have exactly one solut…

题目链接:Path Sum II | LeetCode OJ Given a binary tree and a sum, find all root-to-leaf paths where each path's sum equals the given sum. For example: Given the below binary tree and sum = 22, 5 / \ 4 8 / / \ 11 13 4 / \ / \ 7 2 5 1 return [ [5,4,11,2],…

题目链接:Path Sum | LeetCode OJ Given a binary tree and a sum, determine if the tree has a root-to-leaf path such that adding up all the values along the path equals the given sum. For example: Given the below binary tree and sum = 22, 5 / \ 4 8 / / \ 11…

题目链接:Balanced Binary Tree | LeetCode OJ Given a binary tree, determine if it is height-balanced. For this problem, a height-balanced binary tree is defined as a binary tree in which the depth of the two subtrees of every node never differ by more tha…

题目链接:Same Tree | LeetCode OJ 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. Tags: Depth-first Search 分析 很基本的一道深度优…

题目链接:Recover Binary Search Tree | LeetCode OJ 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 constan…

题目链接:Validate Binary Search Tree | LeetCode OJ 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…

题目链接:Symmetric Tree | LeetCode OJ Given a binary tree, check whether it is a mirror of itself (ie, symmetric around its center). For example, this binary tree is symmetric: 1 / \ 2 2 / \ / \ 3 4 4 3 But the following is not: 1 / \ 2 2 \ \ 3 3 Note: B…

题目链接:Sudoku Solver | LeetCode OJ 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 n…

题目链接:Valid Sudoku | LeetCode OJ 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 '.'. A partially filled sudoku which is valid. Note:…

题目链接:Populating Next Right Pointers in Each Node II | LeetCode OJ Follow up for problem "Populating Next Right Pointers in Each Node". What if the given tree could be any binary tree? Would your previous solution still work? Note: You may only u…

题目链接:Populating Next Right Pointers in Each Node | LeetCode OJ Given a binary tree struct TreeLinkNode { TreeLinkNode *left; TreeLinkNode *right; TreeLinkNode *next; } Populate each next pointer to point to its next right node. If there is no next ri…

LeetCode:Path Sum Given a binary tree and a sum, determine if the tree has a root-to-leaf path such that adding up all the values along the path equals the given sum. For example:Given the below binary tree and sum = 22, 5 / \ 4 8 / / \ 11 13 4 / \ \…

目录 leetcode笔记 动态规划在字符串匹配中的应用 0 参考文献 1. [10. Regular Expression Matching] 1.1 题目 1.2 思路 && 解题方法 1.3 实现 2. [44. Wildcard Matching] 2.1 题目 2.2 思路 && 解题方法 2.3 实现 3. [97. Interleaving String] 3.1 题目 3.2 思路 && 解题方法 3.3 实现 leetcode笔记 动态规划…

剑指offer 65. 不用加减乘除做加法(Leetcode 371. Sum of Two Integers) https://leetcode.com/problems/sum-of-two-integers/ 题目: 写一个函数,求两个整数之和,要求在函数体内不得使用加减乘除这四个符号. 分析: 对于不能使用正常的四则运算符,一般就是使用位运算了.而本题要想实现加法,只能使用异或了. 需要注意的是,加法的时候涉及进位,而进位的实现利用与运算. 此外,进位之后还有可能产生进位,所以要在循环里…

0.问题描述 给定一个排序数组和一个目标值,在数组中找到目标值,并返回其索引.如果目标值不存在于数组中,返回它将会被按顺序插入的位置. 你可以假设数组中无重复元素. 示例 1: 12 输入: [1,3,5,6], 5输出: 2 示例 2: 12 输入: [1,3,5,6], 2输出: 1 示例 3: 12 输入: [1,3,5,6], 7输出: 4 示例 4: 12 输入: [1,3,5,6], 0输出: 0 1.问题分析 典型的二分查找,虽然不知道leetcode的数据为什么暴力搜索比二分法的…

Design and implement a TwoSum class. It should support the following operations: add and find. add - Add the number to an internal data structure.find - Find if there exists any pair of numbers which sum is equal to the value. 这个解法很容易想到,但很容易超时. 基本来说有…

题目描述 给定一个无重复的正整数数组 candidates 和一个正整数 target, 求所有和为 target 的 candidates 中数的组合中.其中相同数的不同顺序组合算做同一种组合,candidates 中的数可以重复使用. 算法一 首先想到的方法就是枚举所有的组合可能性,判断其和是否为target.枚举的方法可以使用递归,对candidates中每一个数,有“加入组合”和“不加入组合”两种选择,每一种选择又可以向后面元素的不同选择递归,直到candidate中最后一个元素.可以用…

question: Calculate the sum of two integers a and b, but you are not allowed to use the operator + and -. my wrong answer 错误点: 显示memory error 应该是运行较大数字时导致内存不够,所以这种方法不佳 正确答案地址:(暂时不明白) http://blog.csdn.net/mebiuw/article/details/51788817 http://www.cnb…

一. 题目描写叙述 Given an integer array nums, find the sum of the elements between indices i and j (i ≤ j), inclusive. The update(i, val) function modifies nums by updating the element at index i to val. Example: Given nums = [1, 3, 5] sumRange(0, 2) -> 9 u…

You are given a binary tree in which each node contains an integer value. Find the number of paths that sum to a given value. The path does not need to start or end at the root or a leaf, but it must go downwards (traveling only from parent nodes to…

Given an integer array with all positive numbers and no duplicates, find the number of possible combinations that add up to a positive integer target. Example: nums = [1, 2, 3] target = 4 The possible combination ways are: (1, 1, 1, 1) (1, 1, 2) (1,…

Given a non-empty 2D matrix matrix and an integer k, find the max sum of a rectangle in the matrix such that its sum is no larger than k. Example: Given matrix = [ [1, 0, 1], [0, -2, 3] ] k = 2 The answer is 2. Because the sum of rectangle [[0, 1], […

Given a 2D matrix matrix, find the sum of the elements inside the rectangle defined by its upper left corner (row1, col1) and lower right corner (row2, col2). The above rectangle (with the red border) is defined by (row1, col1) = (2, 1) and (row2, co…

Given an integer array nums, find the sum of the elements between indices i and j (i ≤ j), inclusive. The update(i, val) function modifies nums by updating the element at index i to val. Example: Given nums = [1, 3, 5] sumRange(0, 2) -> 9 update(1, 2…

Given a 2D matrix matrix, find the sum of the elements inside the rectangle defined by its upper left corner (row1, col1) and lower right corner (row2, col2). The above rectangle (with the red border) is defined by (row1, col1) = (2, 1) and (row2, co…

Given an integer array nums, find the sum of the elements between indices i and j (i ≤ j), inclusive. Example: Given nums = [-2, 0, 3, -5, 2, -1] sumRange(0, 2) -> 1 sumRange(2, 5) -> -1 sumRange(0, 5) -> -3 Note: You may assume that the array do…

Find all possible combinations of k numbers that add up to a number n, given that only numbers from 1 to 9 can be used and each combination should be a unique set of numbers. Ensure that numbers within the set are sorted in ascending order. Example 1…

Design and implement a TwoSum class. It should support the following operations:add and find. add - Add the number to an internal data structure.find - Find if there exists any pair of numbers which sum is equal to the value. For example,add(1); add(…

Given an array of integers that is already sorted in ascending order, find two numbers such that they add up to a specific target number.The function twoSum should return indices of the two numbers such that they add up to the target, where index1 mu…