GitHub - wolf5x/leetcode: solution for leetcode.com

3Sum Closest	O(n^2) 求三个数字之和最接近target的数字,排序后循环一层,接下去两端向中间靠拢	80ms
3Sum	O(n^2) 求3个数字之和为0的组合,同上,注意去重	250ms
4Sum	O(n^3) 求4个数字之和为0的组合,同3Sum,第三层循环两端向中间靠拢	250ms
4Sum	O(n^2log(n))+大常数将原数组两两相加组成一个二元组(num[i]+num[j],i,j),接着对原数组两层for循环并对二元组二分取值,用下标保证不重复	1100ms
Add Binary	模拟二进制加法,一个for循环	20ms
Add Two Numbers	链表加法,同上,一个for循环	200ms
Anagrams	选取strs中由相同字符构成的串,用map<\string,vector<\string> >解决,排序后的str做key,然后把原值塞进vector中	250ms
Balanced Binary Tree	检查是否是二叉平衡树,任意节点的左右子树高度差不超过1,递归解决	68ms
Best Time to Buy and Sell Stock III	O(n) 知道股票每日价格,只能交易两笔,卖了之后才能买,两边DP	60ms
Best Time to Buy and Sell Stock II	O(n) 知道股票每日价格,可以交易任意笔,差值求和	48ms
Best Time to Buy and Sell Stock	O(n) 知道股票每日价格,只能交易一笔,记录最小值	56ms
Binary Tree Inorder Traversal	in-order遍历二叉树	12ms
Binary Tree Level Order Traversal II	简单遍历二叉树,从叶子到根的顺序装进vector	132ms
Binary Tree Level Order Traversal	简单遍历二叉树,从根到叶子的顺序装进vector	24ms
Binary Tree Maximum Patd Sum	简单树形DP，权值之和最大的一段路径特别要注意负数	152ms
Binary Tree Zigzag Level Order Traversal	简单遍历二叉树,从根到叶子,奇数层从左到右,偶数层从右到左	28ms
Climbing Stairs	Fibonacci	12ms
Combination Sum II	简单递归,从数组C中找一些数字组使这些数字和为T,一个数字用一次,且答案不能重复	60ms
Combination Sum	简单递归,从数组C中找一些数字组使这些数字和为T,一个数字用任意次	60ms
Combinations	简单递归,列出所有k个数字(1-n)的组合	56ms
Construct Binary Tree from Inorder and Postorder Traversal	知道中序和后序，构建树，要注意内存	168ms
Construct Binary Tree from Preorder and Inorder Traversal	知道中序和前序，构建树，要注意内存	176ms
Container With Most Water	一排直线,找两条线使得能装下的水最多	100ms
Convert Sorted Array to Binary Search Tree	以排好序的数组生成BST,找到中间节点,用preorder生成	92ms
Convert Sorted List to Binary Search Tree	已排好序的链表生成BST,先得到长度,然后用inorder来生成	164ms
Count and Say	简单模拟 1->11->21->1211->...	20ms
Decode Ways	简单DP O(n) 把字符串分段使得每一段都是1-26的方法数	16ms
Distinct Subsequences	简单DP O(n*m) 有多少个S的子串包含T 注意边界	72ms
Divide Two Integers	模拟除法,用位运算,注意边界,int转正数会溢出,转成负数做	64ms
Edit Distance	O(n*m) 最短编辑距离注意边界	140ms
First Missing Positive	找到最小不存在的正整数,O(1)空间	20ms
Flatten Binary Tree to Linked List	将二叉树重构,只有右儿子	52ms
Generate Parentheses	简单递归生成匹配的括号	12ms
Gray Code	格雷码公式i^(i>>1)	36ms
Implement strStr()	KMP	28ms
Insert Interval	一个区间和一组有序区间合并	72ms
Integer to Roman	数字翻译成罗马数字	128ms
Interleaving String	看s1和s2能不能合并成s3	16ms
Jump Game II	每个位子可以跳到val远处,问起点到终点的最小步数	52ms
Jump Game	每个位子可以跳到val远处,问起点能不能跳到终点	52ms
Largest Rectangle in Histogram	经典问题,最大矩形 left+right	100ms
Largest Rectangle in Histogram	用一个递增栈来做	100ms
Length of Last Word	最后一个词的长度优美解法	32ms
Letter Combinations of a Phone Number	递归手机号码和字符的组合数	12ms
Longest Common Prefix	一组字符串的最长相同前缀	24ms
Longest Consecutive Sequence	乱序数组中最长的连续数字用unordered_set O(n)	64ms
Longest Palindromic Substring	最长回文 O(n)	40ms
Longest Substring Without Repeating Characters	字符串中最长不重复的字符纯O(n) 两种做法,比较优美	50ms
Longest Valid Parentheses	最长合法圆括号数	40ms
Maximal Rectangle	二维的Largest Rectangle in Histogram	72ms
Maximum Depth of Binary Tree	树的最长深度	44ms
Maximum Subarray	最大子序列	44ms
Median of Two Sorted Arrays	两个排序数组的中位数	192ms
Merge Intervals	合并区间 O(nlogn)	88ms
Merge k Sorted Lists	合并k个有序链表 O(nlogm) 注意写比较器	84ms
Merge Sorted Array	将有序数组A,B合并到A中,O(1)内存,倒序	32ms
Merge Two Sorted Lists	合并两个有序链表,新链表要用原链表拼接	60ms
Minimum Depth of Binary Tree	根节点到最近的叶子节点的距离	52ms
Minimum Path Sum	从左上角向下向右走到右下角的最短距离简单二维DP	76ms
Minimum Window Substring	从S中找到包含T所有字符的最小子串 , O(n)	60ms
Multiply Strings	大数乘法	36ms
N-Queens II	输出方案数位运算	60ms
N_Queens	输出方案同上	16ms
Next Permutation	下一个组合数，要求O(n)	68ms
Palindrome Number	判断数字回文 O(1)空间	288ms
Palindrome Partitioning II	最小几刀将一个串切成全部都是回文串	188ms
Palindrome Partitioning	将一个串切分成全部都是回文串	52ms
Partition List	将链表中小于x的归到左边,并保持原顺序不变	48ms
Pascal's Triangle II	杨辉三角 O(n)空间输出第n行	8ms
Pascal's Triangle	杨辉三角	16ms
Path Sum II	输出从根节点到叶子距离为sum的path	72ms
Path Sum	跟加点到叶子的距离是否有和为sum	64ms
Permutation Sequence	第K个组合数	12ms
Permutations II	有相同数字的组合数	164ms
Permutations	不同数字的组合数	84ms
Plus One	大数+1	20ms
Populating Next Right Pointers in Each Node II	任意二叉树的邻指针用O(1)的空间bfs	160ms
Populating Next Right Pointers in Each Node	完全二叉树的邻指针	128ms
Pow(x, n)	模拟pow(double,int) 注意n的int范围,正负	20ms
Recover Binary Search Tree	树中两个元素错位，要求修复并用O(1)的空间，前序遍历记录上一个节点	308ms
Regular Expression Matching	正则表达式.*匹配	48ms
Remove Duplicates from Sorted Array II	使有序数组中只保留最多两份相同数字	92ms
Remove Duplicates from Sorted Array	把有序数组中相同的数字去掉	68ms
Remove Duplicates from Sorted List II	有序链表中将有重复的数字全部去掉	68ms
Remove Duplicates from Sorted List	有序链表去重	80ms
Remove Element	给一个元素和一个数组,把这个数组中等于这个元素的去掉	20ms
Remove Nth Node From End of List	把指针的倒数第N个节点去掉	20ms
Restore IP Addresses	一串数字,转成IP地址	24ms
Reverse Integer	翻转int	32ms
Reverse Linked List II	链表n到m个数字翻转	20ms
Reverse Nodes in k-Group	将链表以k个一组翻转	144ms
Roman to Integer	罗马数字转阿拉伯数字	172ms
Rotate Image	顺时针翻转n*n矩阵,in-place	32ms
Rotate List	将链表右移k位	72ms
Same Tree	判断两个二叉树是否相等	12ms
Scramble String	判断一个字符串能否以二叉树选择成另外一个,O(n^3)空间,O(n^4)时间	76ms
Search a 2D Matrix	在n*m的有序矩阵中找一个数	72ms
Search for a Range	lower_bound和upper_bound	68ms
Search in Rotated Sorted Array II	同上题,不过有有重复数字,极限情况会退化成O(n)	56ms
Search in Rotated Sorted Array	在旋转过的且唯一的有序数组中二分查找	24ms
Search Insert Position	lower_bound	40ms
Set Matrix Zeroes	如果有某个数字是0,那么把这行这列都设置为0,in-place,用第一行第一列记录,注意顺序	372ms
Simplify Path	将unix的文件路径化简,用stringstream和栈来做	48ms
Sort Colors	0,1,2数组的排序,一个循环	28ms
Spiral Matrix II	回字形填充矩阵	24ms
Spiral Matrix	回字形遍历矩阵	16ms
Sqrt(x)	模拟整数开平方 , 二分 , 用除法	48ms
String to Integer (atoi)	模拟atoi , 只返回第一部分的值 , 注意int范围	52ms
Subsets II	有重复数字的所有子串	60ms
Subsets	组数的子串	40ms
Substring with Concatenation of All Words	在S中找到恰好包含vector L的所有子串 O(S.length() * L[0].length())	244
Sudoku Solver	解数独,唯一解,dfs	24ms
Sum Root to Leaf Numbers	二叉树根到叶子的组成的数字的和	24ms
Surrounded Regions	将被X包围的O变成X	48ms
Swap Nodes in Pairs	交换链表奇偶的节点	20ms
Symmetric Tree	判断树是否对称	24ms
Text Justification	文字排版	12ms
Trapping Rain Water	一个数组代表木条的高度,问这组容器能积多少水 , 一次循环,两边向中间	56ms
Triangle	数塔	44ms
Two Sum	找两个数字和等于target	28ms
Unique Binary Search Trees II	输出BST的所有方案	120ms
Unique Binary Search Trees	输出BST的所有方案数	68ms
Unique Paths II	从左上角走到右下角的方案数,有障碍物	24ms
Unique Paths	从左上角走到右下角的方案数	12ms
Valid Number	判断字符串是否是个合法数字, " -1.2e+3 " 9个状态的自动机	24ms
Valid Palindrome	判断一个字符串是否是回文,只考虑大小写数字,大小写不care	52ms
Valid Parentheses	判断(){}[]是否合法,stack O(n)	48ms
Valid Sudoku	判断数独已经填了的数字是否冲突	48ms
Validate Binary Search Tree	判断一个树是否是BST	64ms
Wildcard Matching	模拟通配符匹配 O(1)空间	88ms
Word Ladder II	从一个词到另一个词的方案,要求相邻的单词相差1且出现才多给的词典中	1036ms
Word Ladder	从一个词到另一个词的距离,要求相邻的单词相差1且出现才多给的词典中	1004ms
Word Search	在二维矩阵中找一个串,字母不能重复用,暴力dfs	88ms
ZigZag Conversion	Z字型遍历字符串	92ms

Name		Name	Last commit message	Last commit date
Latest commit History 22 Commits
3Sum Closest.cpp		3Sum Closest.cpp
3Sum.cpp		3Sum.cpp
4Sum.cpp		4Sum.cpp
Add Binary.cpp		Add Binary.cpp
Add Two Numbers.cpp		Add Two Numbers.cpp
Anagrams.cpp		Anagrams.cpp
Balanced Binary Tree.cpp		Balanced Binary Tree.cpp
Best Time to Buy and Sell Stock .cpp		Best Time to Buy and Sell Stock .cpp
Best Time to Buy and Sell Stock II.cpp		Best Time to Buy and Sell Stock II.cpp
Best Time to Buy and Sell Stock III.cpp		Best Time to Buy and Sell Stock III.cpp
Binary Tree Inorder Traversal.cpp		Binary Tree Inorder Traversal.cpp
Binary Tree Level Order Traversal II.cpp		Binary Tree Level Order Traversal II.cpp
Binary Tree Level Order Traversal.cpp		Binary Tree Level Order Traversal.cpp
Binary Tree Maximum Path Sum.cpp		Binary Tree Maximum Path Sum.cpp
Binary Tree Zigzag Level Order Traversal.cpp		Binary Tree Zigzag Level Order Traversal.cpp
Climbing Stairs.cpp		Climbing Stairs.cpp
Combination Sum II.cpp		Combination Sum II.cpp
Combination Sum.cpp		Combination Sum.cpp
Combinations.cpp		Combinations.cpp
Construct Binary Tree from Inorder and Postorder Traversal.cpp		Construct Binary Tree from Inorder and Postorder Traversal.cpp
Construct Binary Tree from Preorder and Inorder Traversal.cpp		Construct Binary Tree from Preorder and Inorder Traversal.cpp
Container With Most Water.cpp		Container With Most Water.cpp
Convert Sorted Array to Binary Search Tree.cpp		Convert Sorted Array to Binary Search Tree.cpp
Convert Sorted List to Binary Search Tree.cpp		Convert Sorted List to Binary Search Tree.cpp
Count and Say.cpp		Count and Say.cpp
Decode Ways.cpp		Decode Ways.cpp
Distinct Subsequences.cpp		Distinct Subsequences.cpp
Divide Two Integers.cpp		Divide Two Integers.cpp
Edit Distance.cpp		Edit Distance.cpp
First Missing Positive.cpp		First Missing Positive.cpp
Flatten Binary Tree to Linked List.cpp		Flatten Binary Tree to Linked List.cpp
Generate Parentheses.cpp		Generate Parentheses.cpp
Gray Code.cpp		Gray Code.cpp
Implement strStr().cpp		Implement strStr().cpp
Insert Interval.cpp		Insert Interval.cpp
Integer to Roman.cpp		Integer to Roman.cpp
Interleaving String.cpp		Interleaving String.cpp
Jump Game II.cpp		Jump Game II.cpp
Jump Game.cpp		Jump Game.cpp
Largest Rectangle in Histogram.cpp		Largest Rectangle in Histogram.cpp
Length of Last Word.cpp		Length of Last Word.cpp
Letter Combinations of a Phone Number.cpp		Letter Combinations of a Phone Number.cpp
Longest Common Prefix.cpp		Longest Common Prefix.cpp
Longest Consecutive Sequence.cpp		Longest Consecutive Sequence.cpp
Longest Palindromic Substring.cpp		Longest Palindromic Substring.cpp
Longest Substring Without Repeating Characters.cpp		Longest Substring Without Repeating Characters.cpp
Longest Valid Parentheses.cpp		Longest Valid Parentheses.cpp
Maximal Rectangle.cpp		Maximal Rectangle.cpp
Maximum Depth of Binary Tree.cpp		Maximum Depth of Binary Tree.cpp
Maximum Subarray.cpp		Maximum Subarray.cpp
Median of Two Sorted Arrays.cpp		Median of Two Sorted Arrays.cpp
Merge Intervals.cpp		Merge Intervals.cpp
Merge Sorted Array.cpp		Merge Sorted Array.cpp
Merge Two Sorted Lists.cpp		Merge Two Sorted Lists.cpp
Merge k Sorted Lists.cpp		Merge k Sorted Lists.cpp
Minimum Depth of Binary Tree.cpp		Minimum Depth of Binary Tree.cpp
Minimum Path Sum.cpp		Minimum Path Sum.cpp
Minimum Window Substring.cpp		Minimum Window Substring.cpp
Multiply Strings.cpp		Multiply Strings.cpp
N_Queens II.cpp		N_Queens II.cpp
N_Queens.cpp		N_Queens.cpp
Next Permutation.cpp		Next Permutation.cpp
Palindrome Number.cpp		Palindrome Number.cpp
Palindrome Partitioning II.cpp		Palindrome Partitioning II.cpp
Palindrome Partitioning.cpp		Palindrome Partitioning.cpp
Partition List.cpp		Partition List.cpp
Pascal's Triangle II.cpp		Pascal's Triangle II.cpp
Pascal's Triangle.cpp		Pascal's Triangle.cpp
Path Sum II.cpp		Path Sum II.cpp
Path Sum.cpp		Path Sum.cpp
Permutation Sequence.cpp		Permutation Sequence.cpp
Permutations II.cpp		Permutations II.cpp
Permutations.cpp		Permutations.cpp
Plus One.cpp		Plus One.cpp
Populating Next Right Pointers in Each Node II.cpp		Populating Next Right Pointers in Each Node II.cpp
Populating Next Right Pointers in Each Node.cpp		Populating Next Right Pointers in Each Node.cpp
Pow(x, n).cpp		Pow(x, n).cpp
README.md		README.md
Recover Binary Search Tree.cpp		Recover Binary Search Tree.cpp
Regular Expression Matching.cpp		Regular Expression Matching.cpp
Remove Duplicates from Sorted Array II.cpp		Remove Duplicates from Sorted Array II.cpp
Remove Duplicates from Sorted Array.cpp		Remove Duplicates from Sorted Array.cpp
Remove Duplicates from Sorted List II.cpp		Remove Duplicates from Sorted List II.cpp
Remove Duplicates from Sorted List.cpp		Remove Duplicates from Sorted List.cpp
Remove Element.cpp		Remove Element.cpp
Remove Nth Node From End of List.cpp		Remove Nth Node From End of List.cpp
Restore IP Addresses.cpp		Restore IP Addresses.cpp
Reverse Integer.cpp		Reverse Integer.cpp
Reverse Linked List II.cpp		Reverse Linked List II.cpp
Reverse Nodes in k-Group.cpp		Reverse Nodes in k-Group.cpp
Roman to Integer.cpp		Roman to Integer.cpp
Rotate Image.cpp		Rotate Image.cpp
Rotate List.cpp		Rotate List.cpp
Same Tree.cpp		Same Tree.cpp
Scramble String.cpp		Scramble String.cpp
Search Insert Position.cpp		Search Insert Position.cpp
Search a 2D Matrix.cpp		Search a 2D Matrix.cpp
Search for a Range.cpp		Search for a Range.cpp
Search in Rotated Sorted Array II.cpp		Search in Rotated Sorted Array II.cpp
Search in Rotated Sorted Array.cpp		Search in Rotated Sorted Array.cpp

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