通配符匹配 Wildcard Matching
2018-06-12
通配符匹配问题： https://leetcode.com/problems/wildcard-matching/ Given an input string (s) and a pattern (p), implement wildcard pattern matching with support for ‘?’ and ‘*’. ‘?’ Matches any single character. ‘*’ Matches any sequence of characters (including the empty sequence). The matching should cover the entire input string (not partial). Note: s could be empty and contains only lowercase letters a-z. p could be empty and contains only lowercase letters a-z, and characters like ? or *. 待匹配字串 s 中只有字母，模式串中 p 只含有字母和 ?、*，? 匹配任意单个字符，* 匹配任意多个字符（包括空字串），判断字串是否完全匹配。 使用递归算法会超时。 …
Best Time to Buy and Sell Stock III
2018-05-04
股票买入卖出的最佳时间问题： https://leetcode.com/problems/best-time-to-buy-and-sell-stock-iii/ Say you have an array for which the ith element is the price of a given stock on day i. Design an algorithm to find the maximum profit. You may complete at most two transactions. Note: You may not engage in multiple transactions at the same time (i.e., you must sell the stock before you buy again). Example 1: Input: [3,3,5,0,0,3,1,4] Output: 6 Explanation: Buy on day 4 (price = 0) and sell on day 6 (price = 3), profit = 3-0 = 3. Then buy on day 7 (price = 1) and sell on day 8 (price = 4), profit = 4-1 = 3. Example 2: Input: [1,2,3,4,5] Output: 4 Explanation: Buy on day 1 (price = 1) and sell on day 5 (price = 5), profit = 5-1 = 4. Note that you cannot buy on day 1, buy on day 2 and sell them later, as you are engaging multiple transactions at the same time. You must sell before buying again. Example 3: Input: [7,6,4,3,1] Output: 0 Explanation: In this case, no transaction is done, i.e. max profit = 0. 意即给定一个数组，数组下标表示时间，元素值表示股票价格，买入、卖出最多两次，且买入前必须先卖出，求最大利润。 …