题目：
Given a 2D board and a word, find if the word exists in the grid.
The word can be constructed from letters of sequentially adjacent cell, where "adjacent" cells are those horizontally or ver...
分类：
编程语言 时间：
2015-01-15 16:14:27
阅读次数：
301
题目：
Given a digit string, return all possible letter combinations that the number could represent.
A mapping of digit to letters (just like on the telephone buttons) is given below.
Input:D...
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编程语言 时间：
2015-01-11 14:56:20
阅读次数：
236
题目：
The gray code is a binary numeral system where two successive values differ in only one bit.
Given a non-negative integer n representing the total number of bits in the code, print the seque...
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编程语言 时间：
2015-01-11 12:27:43
阅读次数：
282
题目：
Given n pairs of parentheses, write a function to generate all combinations of well-formed parentheses.
For example, given n = 3, a solution set is:
"((()))", "(()())", "(())()", "()(()...
分类：
编程语言 时间：
2015-01-10 16:42:46
阅读次数：
261
题目：
Given two integers n and k, return all possible combinations of k numbers out of 1 ... n.
For example,
If n = 4 and k = 2, a solution is:
[
[2,4],
[3,4],
[2,3],
[1,2],
[1,3],
...
分类：
编程语言 时间：
2015-01-10 11:20:00
阅读次数：
280
题目：
Given a collection of integers that might contain duplicates, S, return all possible subsets.
Note:
Elements in a subset must be in non-descending order.The solution set must not contai...
分类：
编程语言 时间：
2014-12-31 14:41:10
阅读次数：
277
一直以为梯度下降很简单的，结果最近发现我写的一个梯度下降特别慢，后来终于找到原因：step size的选择很关键，有一种叫backtracking line search的梯度下降法就非常高效，该算法描述见下图：下面用一个简单的例子来展示，给一个无约束优化问题：minimize y = (x-3)*...
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其他好文 时间：
2014-12-30 01:40:15
阅读次数：
664
题目：（DP，BackTracking， Greedy，String）Implement wildcard pattern matching with support for'?'and'*'.'?' Matches any single character.'*' Matches any sequ...
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其他好文 时间：
2014-12-27 00:13:18
阅读次数：
292
题目：（Backtracking）The gray code is a binary numeral system where two successive values differ in only one bit.Given a non-negative integernrepresenting...
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其他好文 时间：
2014-12-26 00:54:18
阅读次数：
213
题目：（DP ,BackTracking, String）Implement regular expression matching with support for'.'and'*'.'.' Matches any single character.'*' Matches zero or more...
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其他好文 时间：
2014-12-25 06:34:21
阅读次数：
169
