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LeetCode OJ Edit Distance 题解。

Related to question Excel Sheet Column TitleGiven a column title as appear in an Excel sheet, return its corresponding column number.For example:    A -> 1    B -> 2    C -> 3 

Given an array of size n, find the majority element. The majority element is the element that appears more than ⌊ n/2 ⌋ times.You may assume that the array is non-empty and the majority element al

Given a positive integer, return its corresponding column title as appear in an Excel sheet.For example:    1 -> A    2 -> B    3 -> C    ...    26 -> Z    27 -> AA     

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

Given an array where elements are sorted in ascending order, convert it to a height balanced BST.class Solution {public:vector Num;TreeNode *sortedArrayToBST(vector &num) {if (num.size() == 0) r

Implement regular expression matching with support for '.' and '*'.'.' Matches any single character.'*' Matches zero or more of the preceding element.The matching should cover the entire input st

https://oj.leetcode.com/discuss/366/better-solution-than-brute-force看了下面的评论。思路是：例如"foobarisbarfoobar" ["foo","bar"]，那么将S划分为：1、foo, bar, isb, arf, oob, ar;2、oob, ari, sba, rfo, oba, r

Given n non-negative integers representing an elevation map where the width of each bar is 1, compute how much water it is able to trap after raining.For example, Given [0,1,0,2,1,0,1,3,2,1,2,1]

Reverse bits of a given 32 bits unsigned integer.For example, given input 43261596 (represented in binary as00000010100101000001111010011100), return 964176192 (represented in binary as00111001011

Follow up for "Unique Paths":Now consider if some obstacles are added to the grids. How many unique paths would there be?An obstacle and empty space is marked as 1 and 0 respectively in the

Given a m x n grid filled with non-negative numbers, find a path from top left to bottom right which minimizes the sum of all numbers along its path.Note: You can only move either down or right at

Given an array S of n integers, are there elements a, b, c in S such that a + b + c = 0? Find all unique triplets in the array which gives the sum of zero.Note:Elements in a triplet (a,b,c

Given two integers n and k, return all possible combinations of k numbers out of 1 ... n.For example,If n = 4 and k = 2, a solution is:[ [2,4], [3,4], [2,3], [1,2], [1,3], [1,4],]

Given an array and a value, remove all instances of that value in place and return the new length.The order of elements can be changed. It doesn't matter what you leave beyond the new length.c

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}, 3 / \ 9 20

Given a binary tree, return the bottom-up level order traversal of its nodes' values. (ie, from left to right, level by level from leaf to root).For example:Given binary tree {3,9,20,#,#,15,7},

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,

Given an unsorted array of integers, find the length of the longest consecutive elements sequence.For example,Given [100, 4, 200, 1, 3, 2],The longest consecutive elements sequence is [1, 2, 3

Given two words (start and end), and a dictionary, find all shortest transformation sequence(s) from start to end, such that:Only one letter can be changed at a timeEach intermediate word must exi

Given a linked list, reverse the nodes of a linked listk at a time and return its modified list.If the number of nodes is not a multiple of k then left-out nodes in the end should remain as it is.

Given a string s1, we may represent it as a binary tree by partitioning it to two non-empty substrings recursively.Below is one possible representation of s1 = "great": great / \ gr

这套题的方法和它的前代是一模一样的，找到一个Gap，也就是分界点，这个分界点的前一个元素大于后一个元素。在前代中我们逐步缩小Gap的范围的方法是比较num[l], num[mid], num[h]的值，由于前代中确保不会出现重复的元素，所以这种方法是可行的，但如果有重复元素就会出现无法确定Gap所处范围的问题，比如：3， 1， 3， 3， 3；3， 3， 3，

Given an absolute path for a file (Unix-style), simplify it.For example,path = "/home/", => "/home"path = "/a/./b/../../c/", => "/c"click to show corner cases.Corner Cases:Di

Follow up for "Search in Rotated Sorted Array":What if duplicates are allowed?Would this affect the run-time complexity? How and why?Write a function to determine if a given target is in the

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 diffe

Given s1, s2, s3, find whether s3 is formed by the interleaving of s1 and s2.For example,Given:s1 = "aabcc",s2 = "dbbca",When s3 = "aadbbcbcac", return true.When s3 = "aadbbbaccc", r

There are N children standing in a line. Each child is assigned a rating value.You are giving candies to these children subjected to the following requirements:Each child must have at least on

Write a function that takes an unsigned integer and returns the number of ’1' bits it has (also known as the Hamming weight).For example, the 32-bit integer ’11' has binary representation 000000

Rotate an array of n elements to the right by k steps.For example, with n = 7 and k = 3, the array [1,2,3,4,5,6,7] is rotated to [5,6,7,1,2,3,4].Note:Try to come up as many solutions as yo

https://oj.leetcode.com/discuss/10133/linear-runtime-and-constant-space-solutionclass Solution {public: bool isMatch(const char * s, const char * p) { int posOfStar = -1; // p中最近一次*号的位

class Solution {public: vector > permuteUnique(vector &num) { vector n = num; sort(n.begin(), n.end()); vector ori = n; vector > ans; while (1) {

Given a collection of numbers, return all possible permutations.For example,[1,2,3] have the following permutations:[1,2,3], [1,3,2], [2,1,3], [2,3,1], [3,1,2], and [3,2,1].class Solution {public:

Given a set of candidate numbers (C) and a target number (T), find all unique combinations in C where the candidate numbers sums to T.The same repeated number may be chosen from C unlimited numb

Implement next permutation, which rearranges numbers into the lexicographically next greater permutation of numbers.If such arrangement is not possible, it must rearrange it as the lowest possible

求第k个排列，下面给出一个可以直接求的方法（不用枚举）。http://blog.youkuaiyun.com/modiziri/article/details/22389303截取一段出来：康托展开的公式：（不用记，看形势就行，下面会有例子）X=an*(n-1)!+an-1*(n-2)!+...+ai*(i-1)!+...+a2*1!+a1*0!ai为整数，

Given a set of non-overlapping intervals, insert a new interval into the intervals (merge if necessary).You may assume that the intervals were initially sorted according to their start times.E

class Solution {public: int jump(int A[], int n) { int * step = new int[n]; step[0] = 0; int pos = 1; for (int i = 0; i < n; i++) { int j;

Find the contiguous subarray within an array (containing at least one number) which has the largest sum.For example, given the array [?2,1,?3,4,?1,2,1,?5,4],the contiguous subarray [4,?1,2,1] 

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