jianchao_li
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jianchao_li
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个人介绍
热爱人工智能、机器学习和算法；截至2018年1月2日，LeetCode用户Most Reputation排名第2（https://discuss.leetcode.com/users?section=sort-reputation）
擅长的技术
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发表了文章 2015-06-28
[LintCode] 用栈实现队列
1 class Queue { 2 public: 3 stack stack1; 4 stack stack2; 5 6 Queue() { 7 // do intialization if necessary 8 ...
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发表了文章 2015-06-28
[LintCode] 最长公共子序列
1 class Solution { 2 public: 3 /** 4 * @param A, B: Two strings. 5 * @return: The length of longest common subsequence of A and B.
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发表了文章 2015-06-28
[LintCode] 最长公共子串
1 class Solution { 2 public: 3 /** 4 * @param A, B: Two string. 5 * @return: the length of the longest common substring.
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发表了文章 2015-06-28
[LeetCode] Course Schedule II
Well, this problem is spiritually similar to to Course Schedule. You only need to store the nodes in the order you visit into a vector during BFS or DFS.
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发表了文章 2015-06-28
[LeetCode] Course Schedule
As suggested by the hints, this problem is equivalent to detecting a cycle in the graph represented by prerequisites.
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发表了文章 2015-06-27
[Algorithms] Topological Sort
Topological sort is an important application of DFS in directed acyclic graphs (DAG). For each edge (u, v) from node u to node v in the graph, u must appear before v in the topological sort.
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发表了文章 2015-06-26
[Algorithms] Graph Traversal (BFS and DFS)
Graph is an important data structure and has many important applications. Moreover, grach traversal is key to many graph algorithms.
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发表了文章 2015-06-26
[LeetCode] One Edit Distance
Problem Description: Given two strings S and T, determine if they are both one edit distance apart.
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发表了文章 2015-06-26
[LeetCode] Summary Ranges
This problem is similar to Missing Ranges and easier than that one. The idea is to use two pointers to find the beginning and end of a range and then push it into the result.
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发表了文章 2015-06-25
[LeetCode] Missing Ranges
Problem Description: Given a sorted integer array where the range of elements are [lower, upper] inclusive, return its missing ranges.
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发表了文章 2015-06-25
[LeetCode] Fraction to Recurring Decimal
Well, the key to this problem is on how to identify the recurring parts. After doing some examples using pen and paper, you may find that for the decimal parts to recur, the remainders should recur.
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发表了文章 2015-06-25
[LeetCode] Minimum Size Subarray Sum
The problem statement has stated that there are both O(n) and O(nlogn) solutions to this problem. Let's see the O(n) solution first (taken from this link), which is pretty clever and short.
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发表了文章 2015-06-25
[LeetCode] Reverse Words in a String II
Problem Description: Given an input string, reverse the string word by word. A word is defined as a sequence of non-space characters.
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发表了文章 2015-06-25
[LeetCode] Repeated DNA Sequences
This link has a great discussion about this problem. You may refer to it if you like. In fact, the idea and code in this passage is from the former link.
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发表了文章 2015-06-25
[LeetCode] Word Ladder
Well, this problem has a nice BFS structure. Let's see the example in the problem statement. start = "hit" end = "cog" dict = ["hot", "dot", "dog"...
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发表了文章 2015-06-24
[LeetCode] Surrounded Regions
This problem is not quite difficult (a typical BFS traversal of graph), though, its aceptance rate is relatively low.
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发表了文章 2015-06-24
[LeetCode] Clone Graph
This problem is an application of graph traversal, which has two systematic methods: Bread-First Search (BFS) and Depth-First Search (DFS).
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发表了文章 2015-06-24
[LeetCode] Gas Station
To solve this problem, some observations have to be made first. Let's first see two relatively easy observations.
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发表了文章 2015-06-23
[LeetCode] Number of Islands
This is a typical problem about searching. In fact, you can use either BFS or DFS for it. Personally, I use BFS because I think it is more intuitive and easy to implement.
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发表了文章 2015-06-22
[LeetCode] Basic Calculator II
The basic idea of is as follows: Maintain a deque operands for the numbers and another deque operations for the operators +, -, *,/`.
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发表了文章 2015-06-22
[POJ] Brackets Sequence
This problem can be solved elegantly using dynamic programming. We maintain two arrays: cnt[i][j] --- number of parentheses needed to add within s[i.
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发表了文章 2015-06-19
[Algorithms] KMP
KMP is a classic and yet notoriously hard-to-understand algorithm. However, I think the following two links give nice explanations.
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发表了文章 2015-06-18
[LeetCode] Combination Sum
Well, a typical backtracking problem. Make sure you are clear with the following three problems: What is a partial solution and when is it finished?...
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发表了文章 2015-06-16
[LeetCode] Letter Combinations of a Phone Number
Well, a typical backtracking problem. Make sure you are clear with the following three problems: What is a partial solution and when is it finished?...
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发表了文章 2015-06-16
[LeetCode] Combinations
A typical backtracking problem. For any backtracking problem, you need to be think about three ascepts: What is a partial solution and when is it fi...
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发表了文章 2015-06-15
[Algorithms] Longest Increasing Subsequence
The Longest Increasing Subsequence (LIS) problem requires us to find a subsequence t of a given sequence s, such that t satisfies two requirements: ...
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发表了文章 2015-06-14
[UVa OJ] Longest Common Subsequence
This is the classic LCS problem. Since it only requires you to print the maximum length, the code can be optimized to use only O(m) space (see here).
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发表了文章 2015-06-14
[HackerRank] The Longest Common Subsequence
This is the classic LCS problem. Since it requires you to print one longest common subsequence, just use the O(m*n)-space version here.
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发表了文章 2015-06-13
[Algorithms] Longest Common Subsequence
The Longest Common Subsequence (LCS) problem is as follows: Given two sequences s and t, find the length of the longest sequence r, which is a subsequence of both s and t.
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发表了文章 2015-06-13
[Algorithms] Longest Common Substring
The Longest Common Substring (LCS) problem is as follows: Given two strings s and t, find the length of the longest string r, which is a substring of both s and t.
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发表了文章 2015-06-13
[LeetCode] Longest Valid Parentheses
This problem is a nice extension of the Valid Parentheses problem. There are several ways to solve it.
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发表了文章 2015-06-13
[LeetCode] Generate Parentheses
Well, there are two ways to add a open or close parenthesis to the current string. If number of ( is less than n, you can add (; If number of ) is less than number of (, you can add ).
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发表了文章 2015-06-13
[LeetCode] Valid Parentheses
This is a classic problem of the application of stacks. The idea is, each time we meet a (, { or[, we push it to a stack.
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发表了文章 2015-06-12
[LeetCode] Binary Tree Upside Down
Problem Description: Given a binary tree where all the right nodes are either leaf nodes with a sibling (a left node that shares the same parent node...
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发表了文章 2015-06-12
[LeetCode] Invert Binary Tree
After reading the quote below the problem, you will be motivated to solve it immediately :-) Well, indeed it is also relative easy.
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发表了文章 2015-06-12
[LeetCode] Longest Consecutive Sequence
This problem is not very intuitive at first glance. However, the final idea should be very self-explanatory.
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发表了文章 2015-06-11
[LeetCode] Shortest Palindrome
The idea is to find the longest palindromic substring of s that begins with s[0]. Then take the remaining susbtring, reverse it and append it to the beginning of s.
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发表了文章 2015-06-11
[LeetCode] 4Sum
Well, this problem has a O(n^3) solution similar to 3Sum. That is, fix two elements nums[i] and nums[j] (i < j) and search in the remaining array for ...
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发表了文章 2015-06-10
[LeetCode] 3Sum Closest
This problem is very similar to 3Sum. You only need to maintain a variable for the sum that is closet to target.
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发表了文章 2015-06-10
[LeetCode] 3Sum
This is an extension of the 2Sum problem. The idea is pretty simple (even no need to use hash). Sort the array and then starting from the first elemen...
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发表了文章 2015-06-10
[LeetCode] Word Break II
Well, it seems that many people meet the TLE problem. Well, I use a simple trick in my code to aoivd TLE.
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发表了文章 2015-06-09
[LeetCode] Remove Duplicates from Sorted Array II
Well, an extension of Remove Duplicates from Sorted Array. The program is fairly similar to that in this solution.
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发表了文章 2015-06-09
[LeetCode] Remove Duplicates from Sorted Array
Well, a medium problem. Use two pointers. One points to the curren number and the other points to the last unique number.
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发表了文章 2015-06-09
[Algorithms] Radix Sort
Radix sort is another linear time sorting algorithm. It sorts (using another sorting subroutine) the numbers from their least significant digits to most significant digits.
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发表了文章 2015-06-09
[LeetCode] Largest Number
Well, this problem is designed for radix sort. For more information about radix sort, Introduction to Algorithms, 3rd edition has some nice examples.
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发表了文章 2015-06-09
[Algorithms] Counting Sort
Counting sort is a linear time sorting algorithm. It is used when all the numbers fall in a fixed range.
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发表了文章 2015-06-09
[LeetCode] Sort Colors
The hints on below the problem have suggested a two-pass solution. Now I will focus on the one-pass solution.
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发表了文章 2015-06-09
[LeetCode] Contains Duplicate III
This problem gets much trickier than Contains Duplicate and Contains Duplicate II. The basic idea is to maintain a window of k numbers.
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发表了文章 2015-06-09
[LeetCode] Contains Duplicate
A classic problem of hash set. The unordered_set of C++ is very suitable for this problem. The code is as follows and it should be quite self-explanatory.
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发表了文章 2015-06-08
[LeetCode] Two Sum II - Input array is sorted
Problem Description: 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.
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发表了文章
2018-01-02
Jianchao's Blog is gonna to be moved to Yunqi
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发表了文章
2016-09-10
[LeetCode] Sum of Two Integers
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发表了文章
2016-08-14
[LeetCode] Ransom Note
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发表了文章
2015-12-03
[LeetCode] Sparse Matrix Multiplication
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发表了文章
2015-11-23
[LeetCode] Range Sum Query - Mutable
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发表了文章
2015-11-20
[LeetCode] Additive Number
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发表了文章
2015-11-14
[LeetCode] Number of Islands II
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发表了文章
2015-11-12
[LeetCode] Range Sum Query 2D - Immutable
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发表了文章
2015-11-10
[LeetCode] Range Sum Query - Immutable
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发表了文章
2015-11-08
[LeetCode] Smallest Rectangle Enclosing Black Pixels
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发表了文章
2015-11-05
[LeetCode] Remove Invalid Parentheses
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发表了文章
2015-11-03
[LeetCode] Longest Increasing Subsequence
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发表了文章
2015-10-31
[LeetCode] Bulls and Cows
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发表了文章
2015-10-30
[LeetCode] Binary Tree Longest Consecutive Sequence
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发表了文章
2015-10-30
[LeetCode] Serialize and Deserialize Binary Tree
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发表了文章
2015-10-22
[LeetCode] Best Meeting Point
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发表了文章
2015-10-19
[LeetCode] Find Median from Data Stream
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发表了文章
2015-10-17
[LeetCode] Flip Game II
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发表了文章
2015-10-15
[LeetCode] Flip Game
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发表了文章
2015-10-13
[LeetCode] Nim Game
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