House Robber You are a professional robber planning to rob houses along a street. Each house has a certain amount of money stashed, the only constraint stopping you from robbing each of them is that adjacent houses have security system connected and …

这系列题的背景:有个小偷要偷钱,每个屋内都有一定数额的钱,小偷要发家致富在北京买房的话势必要把所有屋子的钱都偷了,但是屋子之内装了警报器,在一定条件下会触发朝阳群众的电话,所以小偷必须聪明一点,才能保证偷到的钱最多. 问题i:这些屋子排成一排,连续两家失窃就会触发朝阳群众电话 问题ii:这些屋子两成一个圈(四合院既视感),连续两家失窃就会触发朝阳群众电话 问题iii:这些屋子组成一棵树,有连接的两个节点同时失窃就会触发朝阳群众电话 i: 思路:一道典型的dp问题,dp[i]表示在小偷路过第i间房…

Given an array of integers, every element appears twice except for one. Find that single one. 本题利用XOR的特性, X^0 = X, X^X = 0, 并且XOR满足交换律. class Solution(object): def singleNumber(self, nums): """ :type nums: List[int] :rtype: int ""…

I 假设有一个数组,它的第i个元素是一支给定的股票在第i天的价格.如果你最多只允许完成一次交易(例如,一次买卖股票),设计一个算法来找出最大利润. II 假设有一个数组,它的第i个元素是一个给定的股票在第i天的价格.设计一个算法来找到最大的利润.你可以完成尽可能多的交易(多次买卖股票).然而,你不能同时参与多个交易(你必须在再次购买前出售股票). III 假设你有一个数组,它的第i个元素是一支给定的股票在第i天的价格.设计一个算法来找到最大的利润.你最多可以完成两笔交易. 样例 给出一个样例数组…

[1]LeetCode 136 Single Number 题意:奇数个数,其中除了一个数只出现一次外,其他数都是成对出现,比如1,2,2,3,3...,求出该单个数. 解法:容易想到异或的性质,两个相同的数异或为0,那么把这串数从头到尾异或起来,最后的数就是要求的那个数. 代码如下: class Solution { public: int singleNumber(vector<int>& nums) { ; ;i<nums.size();i++) sum ^= nums[i…

1. Given an array of integers, return indices of the two numbers such that they add up to a specific target. 问题: 1.数组是否有序 2. 数组排序 // sorting array Arrays.sort(iArr) 方法1:O(n^2) public class Solution { public int[] twoSum(int[] nums, int target) { int[…

Single Number I : Given an array of integers, every element appears twice except for one. Find that single one. Note: Your algorithm should have a linear runtime complexity. Could you implement it without using extra memory? Solution: 解法不少,贴一种: class…

Best Time to Buy and Sell Stock Say you have an array for which the ith element is the price of a given stock on day i. If you were only permitted to complete at most one transaction (ie, buy one and sell one share of the stock), design an algorithm…

LeetCode:Best Time to Buy and Sell Stock Say you have an array for which the ith element is the price of a given stock on day i. If you were only permitted to complete at most one transaction (ie, buy one and sell one share of the stock), design an a…

Shortest Word Distance Given a list of words and two words word1 and word2, return the shortest distance between these two words in the list. For example,Assume that words = ["practice", "makes", "perfect", "coding"…