2015 年 10月随笔档案 - Tonix

LintCode "k Sum" !!

摘要：Great great DP learning experience:http://www.cnblogs.com/yuzhangcmu/p/4279676.htmlRemember 2 steps of DP: a) setup state transfer equation; b) setup ... 阅读全文

posted @ 2015-10-30 01:22 Tonix 阅读(181) 评论(0) 推荐(0)

LeetCode "Binary Tree Longest Consecutive Sequence"

摘要：A simple application to binary tree traversal.class Solution { typedef pair Rec; // last val - length unsigned ret; void go(TreeNode *p, Rec ... 阅读全文

posted @ 2015-10-28 11:47 Tonix 阅读(164) 评论(0) 推荐(0)

LintCode "Majority Number III"

摘要：Based on Bucketing and "Majority Number I".class Solution { pair majorityNumber0(vector &num) { int count = 0; int ret = 0; fo... 阅读全文

posted @ 2015-10-28 06:10 Tonix 阅读(199) 评论(0) 推荐(0)

LintCode "Previous Permutation"

摘要：A reverse version of the Dictionary algorithm :) If you AC-ed "Next Permutation II", copy it over and just reverse the conditions.class Solution {publ... 阅读全文

posted @ 2015-10-28 05:25 Tonix 阅读(166) 评论(0) 推荐(0)

LintCode "Maximum Subarray III" !

摘要：Such a classic DP.. Thought flow:1. find out the 2 vars in the problem statement: n and k2. setup dp equation - my first thought was by n which was no... 阅读全文

posted @ 2015-10-28 04:27 Tonix 阅读(174) 评论(0) 推荐(0)

LintCode "4 Sum"

摘要：4 Pointer solution. Key: when moving pointers, we skip duplicated ones.Ref: https://github.com/xbz/lintcode/blob/master/4_sum/4sum.cppclass Solution {... 阅读全文

posted @ 2015-10-24 09:17 Tonix 阅读(150) 评论(0) 推荐(0)

LeetCode "Best Meeting Point" !

摘要：Interesting one.. I can feel sparkle in mind in the proposed solution - just pick the mid-point! (yes some boiler-plate code below)class Solution { ... 阅读全文

posted @ 2015-10-23 13:19 Tonix 阅读(191) 评论(0) 推荐(0)

LintCode "Number of Islands II"

摘要：A typical Union-Find one. I'm using a kinda Union-Find solution here. Some boiler-plate code - yeah I know.class Solution { unordered_set hs; // st... 阅读全文

posted @ 2015-10-22 13:15 Tonix 阅读(219) 评论(0) 推荐(0)

LintCode "Find the Weak Connected Component in the Directed Graph"

摘要：New stuff learnt - Union-Find. Simpler and more elegant than I thought.class Solution { unordered_map father; int find(int val) { if(!... 阅读全文

posted @ 2015-10-21 13:09 Tonix 阅读(197) 评论(0) 推荐(0)

LintCode "Triangle Count"

摘要：Should be "Medium" or even "Easy".. Just with a little Greedy.class Solution {public: /** * @param S: A list of integers * @return: An inte... 阅读全文

posted @ 2015-10-21 07:53 Tonix 阅读(258) 评论(0) 推荐(0)

LintCode "Interval Sum II"

摘要：Regular segment tree usage. Should be medium though.struct Node{ Node(int rs, int re) : s(rs), e(re), left(nullptr), right(nullptr){} int s;... 阅读全文

posted @ 2015-10-20 14:40 Tonix 阅读(193) 评论(0) 推荐(0)

LeetCode "Find Median from Data Stream"

摘要：Similar one as LintCode "Data Stream Median".class MedianFinder { priority_queue hl; // max-heap priority_queue, std::greater > hr; // min-heapp... 阅读全文

posted @ 2015-10-20 14:05 Tonix 阅读(152) 评论(0) 推荐(0)

LintCode "Expression Tree Build"

摘要：Lesson learnt: for any calculator problems, keep 2 stacks: 1 for operators and 1 for operands.class Solution { stack op; stack data; void... 阅读全文

posted @ 2015-10-19 14:28 Tonix 阅读(181) 评论(0) 推荐(0)

LintCode "Subarray Sum II"

摘要：Sliding window doesn't work. So it is a typical partial_sum base solution. As below. However if you use a balanced binary search tree, you can get O(n... 阅读全文

posted @ 2015-10-19 04:37 Tonix 阅读(129) 评论(0) 推荐(0)

LintCode "Maximum Subarray Difference"

摘要：A variantion to "largest\smallest consecutive subarray". Idea is, at position i, the current max diff is max(max_left[i] - min_right[i+1], max_right[i... 阅读全文

posted @ 2015-10-18 12:57 Tonix 阅读(151) 评论(0) 推荐(0)

LeetCode "Flip Game II"

摘要：A natural recursion thought.. Please note we can cache intermediate results. class Solution { unordered_map<string, bool> hs; public: bool canWin(stri 阅读全文

posted @ 2015-10-16 11:23 Tonix 阅读(151) 评论(0) 推荐(0)

LintCode "Sliding Window Median" & "Data Stream Median"

摘要：Besides heap, multiset can also be used:class Solution { void removeOnly1(multiset &ms, int v) { auto pr = ms.equal_range(v); ms.e... 阅读全文

posted @ 2015-10-15 14:37 Tonix 阅读(138) 评论(0) 推荐(0)

LintCode "Permutation Index"

摘要：Recursive counting..class Solution { long long w(int n) { long long ret = 1; while(n > 1) { ret *= n; ... 阅读全文

posted @ 2015-10-14 06:55 Tonix 阅读(239) 评论(0) 推荐(0)

LintCode "Count of Smaller Number before itself"

摘要：Warning: input could be > 10000...Solution by segment tree:struct Node{ Node(int s, int e) : start(s), end(e), cnt(0), left(nullptr), right(nullptr... 阅读全文

posted @ 2015-10-13 13:57 Tonix 阅读(155) 评论(0) 推荐(0)

LeetCode "Nim Game"

摘要：Same as LintCode 'Coins in a line'. Here is mind-flow: 4 is a definite lose, for (4 + 1), (4 + 2), (4 + 3), we can put the other player into slot 4 - ... 阅读全文

posted @ 2015-10-13 05:34 Tonix 阅读(183) 评论(0) 推荐(0)

LintCode "Subarray Sum Closest"

摘要：O(nlgn) - my first thought is, keep maintaining a balanced binary search tree, and then use "Binary Search Tree Closest" one to solve it. But unfortun... 阅读全文

posted @ 2015-10-12 02:32 Tonix 阅读(161) 评论(0) 推荐(0)

LeetCode "Word Pattern II"

摘要：Here is the mind flow: we don't know 1st token right? then we try it one by one - recursively.typedef unordered_map HMap;class Solution { bool go(s... 阅读全文

posted @ 2015-10-10 14:42 Tonix 阅读(191) 评论(0) 推荐(0)

LintCode "Minimum Adjustment Cost"

摘要：2D DP. DP is all about choices - current choice with previous choice :) A natural solution as below, and of course we can simply use rolling array for... 阅读全文

posted @ 2015-10-10 07:34 Tonix 阅读(163) 评论(0) 推荐(0)

LintCode "Heapify"

摘要：My first try was, using partial sort to figure out numbers layer by layer in the heap.. it only failed with TLE with the last test case. The problem i... 阅读全文

posted @ 2015-10-09 01:50 Tonix 阅读(222) 评论(0) 推荐(0)

LintCode "Copy Books"

摘要：Classic DP. The initial intuitive O(k*n^2) solution is like this: class Solution { public: /** * @param pages: a vector of integers * @param k: an int 阅读全文

posted @ 2015-10-07 15:12 Tonix 阅读(869) 评论(0) 推荐(0)

LintCode "Maximum Gap"

摘要：Bucketing! A lot of details to take care.struct Bucket{ Bucket() :l(-1), r(-1), bValid(false){};int l, r; bool bValid;};class Solution {public: ... 阅读全文

posted @ 2015-10-07 13:50 Tonix 阅读(176) 评论(0) 推荐(0)

LintCode "Wood Cut"

摘要：Binary search. Please not data types and some details.class Solution {public: /** *@param L: Given n pieces of wood with length L[i] *@para... 阅读全文

posted @ 2015-10-07 11:47 Tonix 阅读(229) 评论(0) 推荐(0)

LintCode "Expression Evaluation"

摘要：This is sth. for me to learn..https://github.com/kamyu104/LintCode/blob/master/C++/expression-evaluation.cpp 阅读全文

posted @ 2015-10-06 15:08 Tonix 阅读(149) 评论(0) 推荐(0)

LintCode "Find Peak Element II"

摘要：Idea is the same: climbing up the hill along one edge (Greedy)! Visualize it in your mind!class Solution {public: /** * @param A: An integer ma... 阅读全文

posted @ 2015-10-06 07:45 Tonix 阅读(164) 评论(0) 推荐(0)

LintCode "Remove Node in Binary Search Tree"

摘要：Not hard to find a solution, but there are several corner cases.class Solution {public: /** * @param root: The root of the binary search tree. ... 阅读全文

posted @ 2015-10-05 06:35 Tonix 阅读(189) 评论(0) 推荐(0)

LintCode "Delete Digits"

摘要：Greedy: remove earliest down-edge: like "54", "97".class Solution {public: /** *@param A: A positive integer which has N digits, A is a string.... 阅读全文

posted @ 2015-10-05 01:14 Tonix 阅读(162) 评论(0) 推荐(0)

LintCode "Binary Representation"

摘要：Not hard to think of a solution. But the key is all details.class Solution {public: /** *@param n: Given a decimal number that is passed in as ... 阅读全文

posted @ 2015-10-04 11:54 Tonix 阅读(158) 评论(0) 推荐(0)

LeetCode "Game of Life"

摘要：A coding practice.class Solution {public: // encoding: 2 - 1 to 0; -1 - 0 to live void gameOfLife(vector>& board) { int h = board.size();... 阅读全文

posted @ 2015-10-04 10:31 Tonix 阅读(182) 评论(0) 推荐(0)

LintCode "Coins in a Line"

摘要：Recursion + Memorized Search(DP). And apparently, the code below can be iterative with only 3 vars - DP.class Solution { unordered_map cache;public... 阅读全文

posted @ 2015-10-03 12:34 Tonix 阅读(138) 评论(0) 推荐(0)

LintCode "Word Break"

摘要：LeetCode AC code failed last case with TLE. We need further pruning - we only enumerate all possible lengths of all dict words.class Solution { vec... 阅读全文

posted @ 2015-10-03 07:02 Tonix 阅读(214) 评论(0) 推荐(0)

LintCode "Max Tree"

摘要：Something new I learnt from it: what is Treap and a O(n) constructionhttps://en.wikipedia.org/wiki/Cartesian_tree#Efficient_constructionclass Solution... 阅读全文

posted @ 2015-10-03 06:23 Tonix 阅读(183) 评论(0) 推荐(0)

LintCode "The Smallest Difference"

摘要：Binary search.class Solution { int _findClosest(vector &A, int v) { int s = 0, e = A.size() - 1; int ret = INT_MAX; while(s... 阅读全文

posted @ 2015-10-02 13:02 Tonix 阅读(273) 评论(0) 推荐(0)

LintCode "Continuous Subarray Sum II"

摘要：Flip over your mind: in rotated subarray case, we can simply cut the continuous smallest subarray.class Solution {public: /** * @param A an int... 阅读全文

posted @ 2015-10-02 00:19 Tonix 阅读(155) 评论(0) 推荐(0)

LintCode "Interleaving Positive and Negative Numbers"

摘要：Partition and swapping. A lot details to take care.class Solution {public: /** * @param A: An integer array. * @return: void */ void... 阅读全文

posted @ 2015-10-01 15:27 Tonix 阅读(163) 评论(0) 推荐(0)

LintCode "Count of Smaller Number"

摘要：Fenwick Tree is perfect for this problem, though space complexity is not quite efficient.class Solution { ////////////////// // Fenwick Tree // ... 阅读全文

posted @ 2015-10-01 11:14 Tonix 阅读(203) 评论(0) 推荐(0)

HackerRank "No Prefix Set"

摘要：Typical Trie usage. But please note that it could be any order of input strings.#include #include #include #include #include #include #include using n... 阅读全文

posted @ 2015-10-01 01:07 Tonix 阅读(353) 评论(0) 推荐(0)

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10 2015 档案