Tonix - 博客园

LeetCode "Copy List with Random Pointer"

摘要： Two passes: all pointer linking info will be recorded in 1st pass - to hashmap; 2nd pass recover the pointer relationship from hashmap.1A!class Soluti... 阅读全文

posted @ 2014-07-23 12:39 Tonix 阅读(151) 评论(0) 推荐(0)

LeetCode "Remove Nth Node From End of List"

摘要： Another Double pointer solution. 1A!class Solution {public: ListNode *removeNthFromEnd(ListNode *head, int n) { ListNode *p = NULL; ... 阅读全文

posted @ 2014-07-23 11:41 Tonix 阅读(125) 评论(0) 推荐(0)

LeetCode "Sqrt(x)"

摘要： 2 solutions: bin-search and Newton iteration.class Solution {public: int _sqrt(long long tgt, long long i0, long long i1) { long long can... 阅读全文

posted @ 2014-07-23 05:41 Tonix 阅读(172) 评论(0) 推荐(0)

LeetCode "Construct Binary Tree from Inorder and Postorder Traversal"

摘要： Another textbook problem. We take back of postorder array as the current root, and then we can split the inorder array: 1st half for current right chi... 阅读全文

posted @ 2014-07-23 04:13 Tonix 阅读(147) 评论(0) 推荐(0)

LeetCode "Construct Binary Tree from Preorder and Inorder Traversal"

摘要： A collegiate textbook problem. Nothing special, but just take care of your memory use.class Solution {public: TreeNode *_buildTree(int pre[], int &... 阅读全文

posted @ 2014-07-23 03:29 Tonix 阅读(128) 评论(0) 推荐(0)

LeetCode "Flatten Binary Tree to Linked List"

摘要： Really interesting BST manipulation problem!class Solution {public: TreeNode *findConn(TreeNode *p) { TreeNode *pTmp = p; while (p... 阅读全文

posted @ 2014-07-22 13:04 Tonix 阅读(127) 评论(0) 推荐(0)

LeetCode "Unique Paths"

摘要： Now I believe thoughts leading to DP is brutal DFS.. DFS is brutal force enumeration, but that's too much and naive. We need pruning. So, DFS + Prunin... 阅读全文

posted @ 2014-07-22 12:12 Tonix 阅读(165) 评论(0) 推荐(0)

LeetCode "Sort Colors"

摘要： For the one pass solution... first I tried to build white\blue from red, but not working anyway. Then I referred someone' code, to build red\blue from... 阅读全文

posted @ 2014-07-22 11:31 Tonix 阅读(134) 评论(0) 推荐(0)

LeetCode "Max Points on a Line "

摘要： The first solution I figured out is O(n^3). I thought it must be O(n^2) to get max points on a line for a given point.. but after checking several art... 阅读全文

posted @ 2014-07-22 06:56 Tonix 阅读(147) 评论(0) 推荐(0)

LeetCode "Generate Parentheses"

摘要： DFS and using stack to validate candidates.class Solution {public: bool isValid(const string &s) { stack stk; for (int i = 0; i &... 阅读全文

posted @ 2014-07-21 11:02 Tonix 阅读(144) 评论(0) 推荐(0)

LeetCode "Plus One"

摘要： The trick is, we can work on a reversed vector - learnt from EPI.class Solution {public: vector plusOne(vector &digits) { std::reverse(digit... 阅读全文

posted @ 2014-07-21 10:32 Tonix 阅读(147) 评论(0) 推荐(0)

LeetCode "Symmetric Tree"

摘要： Recursive.class Solution { public: bool isSymmetric(TreeNode *pl, TreeNode *pr) { if (!pl && !pr) return true; if ((pl && !pr)... 阅读全文

posted @ 2014-07-21 10:19 Tonix 阅读(146) 评论(0) 推荐(0)

LeetCode "Merge Sorted Array"

摘要： My first reaction: move all A elements back by n positions, and start everything from A[0] and B[0]. But a smarter idea is to start everything from th... 阅读全文

posted @ 2014-07-21 10:18 Tonix 阅读(131) 评论(0) 推荐(0)

LeetCode "Balanced Binary Tree"

摘要： Another recursion problem.class Solution {public: int getHeight(TreeNode *p) { if (!p) return 0; int hL = 1; if (p->left) h... 阅读全文

posted @ 2014-07-21 07:38 Tonix 阅读(170) 评论(0) 推荐(0)

LeetCode "N-Queens II"

摘要： Classic recursion\pruning problem. We can use O(n) space: A[i] = j means [i,j] is occupied.class Solution {public: int ret; bool isValid(int *A,... 阅读全文

posted @ 2014-07-21 06:49 Tonix 阅读(125) 评论(0) 推荐(0)

LeetCode "Merge Two Sorted Lists"

摘要： Simply care about the boundary cases:class Solution {public: ListNode *mergeTwoLists(ListNode *l1, ListNode *l2) { if (l1 && !l2) return l1;... 阅读全文

posted @ 2014-07-21 05:53 Tonix 阅读(166) 评论(0) 推荐(0)

LeetCode "Populating Next Right Pointers in Each Node"

摘要： Apparently BFS is the most obvious one.. but it is not that simple - only constant extra space is provided.Then the only strategy to take is recursion... 阅读全文

posted @ 2014-07-21 04:39 Tonix 阅读(270) 评论(0) 推荐(0)

LeetCode "Maximum Subarray"

摘要： Very classic problem. You can brush up your DP and Searching skills.DP:class Solution {public: int maxSubArray(int A[], int n) { // dp[i + 1... 阅读全文

posted @ 2014-07-21 04:19 Tonix 阅读(189) 评论(0) 推荐(0)

LeetCode "Unique Binary Search Trees"

摘要： Another recursion-style problem.1. Each count of sub-solution with a certain root should contribute to final count2. With a certain root, the num of l... 阅读全文

posted @ 2014-07-18 14:13 Tonix 阅读(116) 评论(0) 推荐(0)

LeetCode "Search Insert Position"

摘要： A simple 1D searching problem. Binary search of course.But.. STL has already done it for you:class Solution {public: int searchInsert(int A[], int ... 阅读全文

posted @ 2014-07-18 13:51 Tonix 阅读(95) 评论(0) 推荐(0)

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