08 2015 档案
摘要：This problem is not difficult. But it is not easy to have a bug-free code. As you write your codes according to the hints, the most important thing is...
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摘要：Problem Description:Given a non-empty binary search tree and a target value, findkvalues in the BST that are closest to the target.Note:Given target v...
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摘要：Problem Description:Design an algorithm to encodea list of stringstoa string. The encoded string is then sent over the network and is decoded back to ...
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摘要：1 /** 2 * class VersionControl { 3 * public: 4 * static bool isBadVersion(int k); 5 * } 6 * you can use VersionControl::isBadVersion(k) ...
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摘要：An interesting problem. The code is also short and clear.The basic idea is to use a 2d array dp[i][j] to denote the minimum hp that is required before...
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摘要：Problem Description: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...
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摘要：Problem Description:There is a new alien language which uses the latin alphabet. However, the order among letters are unknown to you. You receive a li...
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摘要：This link has two nice solutions, one updating from forth to back (posted by tqlong in the post) and the other updating from back to forth (posted by ...
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摘要：There are three methods to solve this problem: bit manipulation, rearrangement of the array, and math tricks.Bit Manipulation1 class Solution {2 publi...
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摘要：Problem Description:Given a strings, return all the palindromic permutations (without duplicates) of it. Return an empty list if no palindromic permut...
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摘要：Problem Description:Given a string, determine if a permutation of the string could form a palindrome.For example,"code"-> False,"aab"-> True,"carerac"...
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摘要：The idea and code is just taken from this link. There is a nice explanation to the code on the answer byBrianLuong1337. 1 class Solution { 2 public: 3...
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摘要：Stefan is a hero! Personally, I love his first C++ solution. 1 class Solution { 2 public: 3 int nthUglyNumber(int n) { 4 vector ugly(n, 1)...
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摘要：No matter what language you use on the OJ, you may refer to Stefan's post for a solution. The C++ is rewritten below, just really concise.1 class Solu...
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摘要：The idea is very simple: just extract the numbers from each version number and compare the numbers from beginning to the end. However, C++ seems to ha...
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摘要：The basic idea is to store the key-value pair in some container. In the following code, we make three type definitions:1 typedef list LI;2 typedef pai...
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摘要：The idea is similar to Strobogrammatic Number II: generate all those in-range strobogrammatic numbers and count.You may refer to this link for a very ...
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摘要：Problem Description:Givennnodes labeled from0ton - 1and a list of undirected edges (each edge is a pair of nodes), write a function to check whether t...
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摘要：A typical DFS problem. Just go ahead... 1 class Solution { 2 public: 3 bool exist(vector>& board, string word) { 4 int m = board.size(), n...
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摘要：A simple combination of Implement Trie (Prefix Tree) and Word Search. If you've solved them, this problem will become easy :-)The following code is ba...
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摘要：You need to understand what a Trie is before writing the code :-) This link has a nice solution, whose code is rewritten below. 1 class TrieNode { 2 p...
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摘要：This problem is purely to test your coding ability. Just go ahead :-) 1 class Solution { 2 public: 3 string countAndSay(int n) { 4 string ...
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摘要：Try to split all the numbers into two groups with each of the target one in different groups. Refer to this link for a nice explanation.The code is wr...
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摘要：Problem Description:Given an array ofnintegersnumsand atarget, find the number of index tripletsi, j, kwith0 & nums, int target) { 4 sort(nums...
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摘要：Well, no matter whether the number is happy or not, its sum-of-squared-digits sequance has a cycle. Well, do you still remember the algorithm for dete...
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摘要：Dynamic ProgrammingThere is a nice introduction to the DP algorithm in thisWikipedia article. The idea is to maintain a running maximumsmaxand a curre...
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摘要：Well, if you have no idea of other methods, try to compue the result for all the numbers ranging from 1 to 20 and then you will see the regularity. Af...
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摘要：The basic idea is to start fromrootand add it to the currentpath, then we recursively visit itsleftandrightsubtrees if they exist; otherwise, we have ...
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摘要：The idea is to add the two binary numbers (represented as strings) from back to forth bit by bit and store the result in the longer string. After the ...
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摘要：This problem is just similar toMinimum Depth of Binary Tree.The first solution also uses recursion (not sure whether it can be called DFS).1 class Sol...
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摘要：Well, this problem has the highest acceptance rate among all OJ problems. It has a very easy 1-line reursive solution. I am not sure whether this one ...
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摘要：The basic idea is to use binary search: keep two pointerslandrfor the current search range, then find the middle elementnums[mid]in this range. Ifnums...
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摘要：The idea is to search for the left and right boundaries of target via two binary searches. Well, some tricks may be needed. Take a look at this link :...
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摘要：The most obvious idea is to maintain two divisors to get the most and least significantdigits and compare them. Well, there are much more clever ideas...
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摘要：The idea is to add the two numbers (represented by linked lists) nodes after nodes and store the result in the longer list. Since we may append the ad...
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摘要：The basic idea is to maintain a hash table for each elementnuminnums, usingnumas key and its index (1-based) as value. For eachnum, search fortarget -...
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摘要：This problem can be solved easily if we are allowed to use more than O(1) space. For example, you may create a copy of the original matrix (O(mn)-spac...
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摘要：This problem is a little tricky at first glance. However, if you have finished theHouse Robberproblem, this problem can simply bedecomposed into two H...
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摘要：Since we are not allowed to rob two adjacent houses, we keep two variablespreandcur. During thei-th loop,prerecords the maximum profit that we do not ...
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摘要：Well, this problem can be solved in 1-line clearly. Take a look at this link:-)1 class Solution {2 public:3 string convertToTitle(int n) {4 ...
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摘要：Problem Description:There are a row ofnhouses, each house can be painted with one of the three colors: red, blue or green. The cost of painting each h...
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摘要：This problem can be solved by DP elegantly. You may refer to this link for the code and explanations.I try to rewrite the code, also in C++, but find ...
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摘要：The idea is just to perform the addition from right to left as usual :-)Note that the result may be longer than the originaldigitsby1number (the carry...
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摘要：The idea is just to add the elements in the spiral order. First the up-most row (u), then the right-most column (r), then the down-most row (d), and f...
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摘要：The idea is just to generate the matrix in the spiral order. First the up-most row (u), then the right-most column (r), then the down-most row (d), an...
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摘要：A simple and in-place idea: first reverse the image in row-major order and then transpose it :-) 1 class Solution { 2 public: 3 void rotate(vector...
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摘要：This problem has a naive solution usingsortand linear scan. The suggested solution uses the idea ofbucket sort. The following is a C++ implementation ...
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摘要：This problem can be solved easily once you find the regularities :-) This link has done it for you. You may refer to its Python version. I rewrite it ...
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摘要：Problem Description:Given an array of meeting time intervals consisting of start and end times[[s1,e1],[s2,e2],...](si& intervals) { 4 sort(in...
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摘要：Problem Description: Given an array of meeting time intervals consisting of start and end times [[s1,e1],[s2,e2],...] (si < ei), determine if a person
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摘要：Problem Description:A strobogrammatic number is a number that looks the same when rotated 180 degrees (looked at upside down).Write a function to dete...
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摘要：Problem Description:This is afollow upofShortest Word Distance. The only difference is now you are given the list of words and your method will be cal...
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摘要：Problem Description:Given a list of words and two wordsword1andword2, return the shortest distance between these two words in the list.For example,Ass...
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摘要：Problem Description: Implement an iterator to flatten a 2d vector.For example,Given 2d vector =[ [1,2], [3], [4,5,6]]By callingnextrepeatedly unti...
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摘要：A relatively difficult tree problem. Well, a recursive solution still gives clean codes. The tricky part of this problem is how to record the result. ...
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摘要：An extension of Best Time to Buy and Sell Stock III. The idea is still to use dynamic programming (see here for detailed introduction). However, in th...
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摘要：Personally, this is a relatively difficult DP problem. This link posts a typical DP solution to it. You may need some time to get how it works.The cod...
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摘要：The function signature has been updated to return a more intuitivevector>which treats a single string as a group of anagrams consisting of only itself...
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摘要：Hash TableThis idea uses a hash table to record the times of appearances of each letter in the two stringssandt. For each letter ins, it increases the...
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摘要：To solve this problem, you first need to understand it well. The key problem is tell the difference of scramble from permutations. You may refer to th...
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