2015年6月3日
[LeetCode] Subsets
摘要： Recursive (Backtracking)This is a typical problem that can be tackled by backtracking.Since backtracking has a more-or-less similar template, so I do ... 阅读全文
posted @ 2015-06-03 00:19 jianchao-li 阅读(218) 评论(0) 推荐(0) 编辑
[LeetCode] Best Time to Buy and Sell Stock II
摘要： This problem is similar toBest Time to Buy and Sell Stock. Givenprices, we find the day (denoted asbuy) of the first local minimum and the day (denote... 阅读全文
posted @ 2015-06-03 00:16 jianchao-li 阅读(179) 评论(0) 推荐(0) 编辑
[LeetCode] Best Time to Buy and Sell Stock
摘要： This post shares a very simple solution, whose code is rewritten below, just 5 lines :-) 1 class Solution { 2 public: 3 int maxProfit(vector& pric... 阅读全文
posted @ 2015-06-03 00:14 jianchao-li 阅读(145) 评论(0) 推荐(0) 编辑
2015年6月2日
[LeetCode] Flatten Binary Tree to Linked List
摘要： This problem seems to be tricky at first glance. However, if you know Morris traversal, it is just the preorder case of Morris traversal and the code ... 阅读全文
posted @ 2015-06-02 23:53 jianchao-li 阅读(185) 评论(0) 推荐(0) 编辑
[LeetCode] Sort List
摘要： There are many merge-sort solutions at the forum, but very few quicksort solutions. So I post my accepted quicksort solution here.Well, after reading ... 阅读全文
posted @ 2015-06-02 23:47 jianchao-li 阅读(201) 评论(0) 推荐(0) 编辑
[LeetCode] Minimum Path Sum
摘要： This is a typical DP problem. Suppose the minimum path sum of arriving at point(i, j)isS[i][j], then the state equation isS[i][j] = min(S[i - 1][j], S... 阅读全文
posted @ 2015-06-02 23:42 jianchao-li 阅读(223) 评论(0) 推荐(0) 编辑
[LeetCode] Unique Paths II
摘要： Well, this problem is similar toUnique Paths. The introduction of obstacles only changes the boundary conditions and make some points unreachable (sim... 阅读全文
posted @ 2015-06-02 23:41 jianchao-li 阅读(153) 评论(0) 推荐(0) 编辑
[LeetCode] Unique Paths
摘要： This is a fundamental DP problem. First of all, let's make some observations.Since the robot can only move right and down, when it arrives at a point,... 阅读全文
posted @ 2015-06-02 23:40 jianchao-li 阅读(203) 评论(0) 推荐(0) 编辑
[LeetCode] Kth Largest Element in an Array
摘要： Well, this problem has a naive solution, which is to sort the array in descending order and return thek-1-th element. However, sorting algorithm gives... 阅读全文
posted @ 2015-06-02 23:39 jianchao-li 阅读(366) 评论(0) 推荐(0) 编辑
[LeetCode] Binary Tree Zigzag Level Order Traversal
摘要： To be honest, this problem is designed to let you use stacks. However, I don't. In fact, you only need to keep a flagand switch it between falseandtru... 阅读全文
posted @ 2015-06-02 23:36 jianchao-li 阅读(173) 评论(0) 推荐(0) 编辑
[LeetCode] Binary Tree Level Order Traversal II
摘要： Well, I do not see what this problem is for. The same code of Binary Tree Level Order Traversal can be used here. The only difference is that we shoul... 阅读全文
posted @ 2015-06-02 23:31 jianchao-li 阅读(174) 评论(0) 推荐(0) 编辑
[LeetCode] Binary Tree Level Order Traversal
摘要： A classic tree traversal problem. I share my two solutions here: BFS and DFS.BFS: 1 vector> levelOrder(TreeNode *root) { 2 vector> levels;... 阅读全文
posted @ 2015-06-02 23:29 jianchao-li 阅读(175) 评论(0) 推荐(0) 编辑
[LeetCode] Binary Tree Postorder Traversal
摘要： This is a fundamental and yet classic problem. I share my three solutions here:Iterative solution using stack ---O(n)time andO(n)space;Recursive solut... 阅读全文
posted @ 2015-06-02 23:27 jianchao-li 阅读(248) 评论(0) 推荐(0) 编辑
[LeetCode] Binary Tree Inorder Traversal
摘要： This is a fundamental and yet classic problem. I share my three solutions here:Iterative solution using stack ---O(n)time andO(n)space;Recursive solut... 阅读全文
posted @ 2015-06-02 23:22 jianchao-li 阅读(256) 评论(0) 推荐(0) 编辑
[LeetCode] Binary Tree Preorder Traversal
摘要： This is a fundamental and yet classic problem. I share my three solutions here:Iterative solution using stack ---O(n)time andO(n)space;Recursive solut... 阅读全文
posted @ 2015-06-02 23:20 jianchao-li 阅读(248) 评论(0) 推荐(0) 编辑