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原创 Sliding Window Maximum

使用deque存数组的索引值，保证deque中元素是降序的，即每次取front就能取到最大元素。class Solution {public: vector maxSlidingWindow(vector& nums, int k) { deque win; vector res; if(nums.

2015-08-15 11:15:52 474

原创 QuickSort 和 QuickSelection中partition注记

CTCI 5th中提到了quicksort partition中的另一种写法，感觉比算法导论上的更容易理解，更直观。其中需要注意的是：1) while(A[left] 2) pivot的选取，可以选取[start, end]中任何一个，或者随机选取。3) return left-1，是partition的左半部分的最有一个元素的Index。Quick Partition

2014-11-28 23:17:55 648

原创任意进制的转换(base2-base36)

思路和普通的十进制转任意进制相同，假设将M进制转N进制，

2014-11-21 10:54:50 3896

转载 autocomplete

1. using Trie with each node attached a list of suggestions.2. using

2014-11-10 21:13:17 472

转载 bit operations topics

source1: Low Level Bit Hacks You Absolutely Must Know

2014-10-30 20:15:41 452

原创 Largest Subtree Which is a Binary Search Tree (BST)

找到一个树中最大的BST subtree，题目来源：http://leetcode.com/2010/11/largest-binary-search-tree-bst-in.html代码

2014-10-30 10:54:39 485

原创 Coins in a Line

题目来源： http://leetcode.com/2011/02/coins-in-line.html二维DP。代码如下：

2014-10-29 21:29:56 457

原创 restore BST from pre-order

#include #include #include using namespace std;struct TreeNode{ int val; TreeNode *left; TreeNode *right; TreeNode(int v): val(v){}};TreeNode *restore(int min, int max, int &idx, vector a

2014-10-28 22:17:50 452

原创 find the N-th node In Inorder

1. Write a function that returns a node in a tree given two parameters: pointer to the root node and the in order traversal number of the node we want to return. The only information stored in the

2014-10-21 15:38:09 448

原创 Find K-th smallest in N sorted arrays

Divide and Conquer, 每次将问题规模缩小

2014-10-20 21:33:08 530

原创 String two pointer swapping (合集)

相关问题：1. Minimum Window Substring

2014-10-20 15:28:32 473

原创 Rotated Sorted Array(合辑)

Corner cases: 1 duplicate elements. 2. the array is not rotated at all.1. Find

2014-10-20 09:56:41 495

原创 Count index of sequence of words

problem source: http://www.careercup.com/question?id=21117662

2014-10-19 11:37:28 496

转载 (MS)Design an algorithm to find the maximum subsquare such that all four borders are filled with bla

Imagine there is a square matrix with n x n cells. Each cell is either filled with a black pixel or a white pixel. Design an algorithm to find the maximum Subsquare such that all four borders are fill

2014-10-19 10:02:58 581

原创整数相加溢出判断

判断两个数相加overflow的代码：int add(int a, int b){ if(((a>>31) & 1) == 0 && ((b>>31) & 1) == 0) { if(a <= INT_MAX-b) return a+b; else return 88888; }

2014-10-18 16:50:53 619

原创 lower_bound和upper_bound的另一种写法

int lower_bound(int A[], int n, int target) { int left = 0, right = n-1; while(left <= right) { int mid = left+(right-left)/2; if(A[mid] < target)

2014-10-15 10:24:11 566

原创 longest substring with two unique charachters

O(n)双指针。code#include #include #include #include #include using namespace std;string longest(string str){ int longest = 0; int longest_start = -1; int occurance[256]; int count = 0

2014-10-14 18:27:46 486

原创 Point inside Triangle/Rectangle Problem

1. 面积法，检查所有边和point围城

2014-10-14 16:35:48 742

原创计算三角形的面积

给出三个点计算三角形的面积。

2014-10-14 16:29:50 807

原创 count duplicate in a sorted array

count insead of find. binary search.#include #include using namespace std;map blist; void count_dup(int* arr, int start, int end){ if(end == start) { blist[arr[start]] +=1;

2014-10-14 12:02:11 554

原创 CTRL+A, CTRL+C, CTRL+V

来源 http://leetcode.com/2011/01/ctrla-ctrlc-ctrlv.html原题的思路不好理解，可以考虑使用冬天

2014-10-13 21:58:49 1259

转载 24点问题算法

DFS

2014-10-13 11:03:07 762

原创 Copy Binary Tree with Random Pointer

similar with the leetcode problem: copy LinkedList with random pointer

2014-10-12 19:35:16 625

转载求分数的循环节和小数表示

参考http://www.cnblogs.com/clive/archive/2009/10/28/Circular_decimal_fraction_USCAO_2_4_5.html

2014-10-12 15:30:00 1746

转载 uva 10716 - Minimum Swap to form Palindrome

转自： http://blog.youkuaiyun.com/chenguolinblog/article/details/7908609

2014-10-07 22:03:33 500

转载 Lowest Common Ancestor

1. 如果只有一次查询，参考

2014-10-07 19:51:52 513

原创 Leetcode第三刷需要注意的问题

2. Reverse Words in a String注意最后一个单词后面的空格。4. Max Points on a Line 注意slope为double类型， infinity是slope的一个特殊值。5. Sort List:需要注意fast slow pointer在只有两个节点时是否能够将list分成两部分。6. Insertion

2014-09-30 08:31:22 601

转载 Max Points on a Line

class Solution {public: int maxPoints(vector &points) { if(points.size() <= 2) return points.size(); int maxpoint = 0; unordered_map hash; f

2014-09-29 16:11:31 372

转载 Maximum Product Subarray

source: http://blog.youkuaiyun.com/sbitswc/article/details/39546719

2014-09-29 15:06:28 380

原创 suffix tree pattern matching

// A simple C++ implementation of substring search using trie of suffixes#include #include #define MAX_CHAR 256using namespace std;// A Suffix Trie (A Trie of all suffixes) Nodeclass SuffixTrie

2014-09-28 16:14:18 574

原创 Interview Set

1. You have an array of n elements, and a sum. Check if any 2 elements in the array sum to the given sum. ( Expected time complexity O(n). Use hashing)

2014-09-13 12:08:41 463

转载 Max Sum in circularly situated Values

Max Sum in circularly situated ValuesThis question was asked first in FACEBOOK On Campus for Internship.There are N trees in a circle. Each tree has a fruit value associated with it. A

2014-09-13 11:53:03 638

原创 Finding all possible simple paths (paths without cycles) between two vertices in a graph

This problem is different from traditional BFS or DFS search, as the previously visited node can be visited again, as they are on different paths.M

2014-09-12 20:28:33 616

转载 Graph Traversal (BFS vs DFS vs Stack)

BFS template: (from wiki)1 procedure BFS(G,v) is2 create a queue Q3 create a set V4 add v to V5 enqueue v onto Q6 while Q is not empty loop7 t ← Q.dequeue()

2014-09-11 15:56:18 834

原创 Text Justification

注意最后一行和只有一个word的行的特殊处理。class Solution {public: vector fullJustify(vector &words, int L) { vector result; if(words.size() == 0) return result; int start = 0;

2014-09-11 11:36:18 359

原创 Divide Two Integers

每次除数增倍，知道

2014-09-10 21:01:31 365

原创 Spiral Matrix

注意细节。class Solution {public: vector spiralOrder(vector > &matrix) { vector result; int row = matrix.size(); if(row == 0) return result; int col = matrix

2014-09-10 20:22:49 365