Sept. 10, 2015 Study again the back tracking algorithm using recursive solution, rat in maze, a classical problem. Made a few of mistakes through the practice, one is how to use two dimension array, another one is that "not all return path returns va…

Backtracking is an algorithm for finding all solutions by exploring all potential candidates. If the solution candidate turns to be not a solution (or at least not the last one), backtracking algorithm discards it by making some changes on the previo…

/* Jeff Somers * * Copyright (c) 2002 * * jsomers@alumni.williams.edu * or * allagash98@yahoo.com * * April, 2002 * * Program: nq * * Program to find number of solutions to the N queens problem. * This program assumes a twos complement architecture.…

Check whether a given graph is Bipartite or not A Bipartite Graph is a graph whose vertices can be divided into two independent sets, U and V such that every edge (u, v) either connects a vertex from U to V or a vertex from V to U. In other words, fo…

问题描述 给定一张迷宫地图和一个迷宫入口,然后进入迷宫探索找到一个出口.如下图所示: 该图是一个矩形区域,有一个入口和出口.迷宫内部包含不能穿越的墙壁或者障碍物.这些障碍物沿着行和列放置,与迷宫的边界平行.迷宫的入口在左上角,出口在右下角. 问题分析 首先要有一张迷宫地图,地图由两部分组成: (1)一是迷宫中各处的位置坐标, (2)二是迷宫各位置处的状态信息,即该处是墙还是路 所以,该迷宫地图可由一个二维数组来表示.数组的横纵坐标表示迷宫各处的位置坐标,数组元素表示各位置处的状态信息. 2.在这…

Leetcode--回溯法常考算法整理 Preface Leetcode--回溯法常考算法整理 Definition Why & When to Use Backtrakcing How to Use Backtracking Leetcode Problems N-Queens Permutations II Combinations Sudoku Solver Definition First, let's see the definition of backtracking given b…

BFS与DFS常考算法整理 Preface BFS(Breath-First Search,广度优先搜索)与DFS(Depth-First Search,深度优先搜索)是两种针对树与图数据结构的遍历或搜索算法,在树与图相关算法的考察中是非常常见的两种解题思路. BFS与DFS常考算法整理 Definition of DFS and BFS How to Implement DFS and BFS DFS How to explore as far as possible How to backt…

区别与联系 区别 DFS多用于连通性问题因为其运行思想与人脑的思维很相似,故解决连通性问题更自然,采用递归,编写简便(但我个人不这样觉得...) DFS的常数时间开销会较少.所以对于一些能用DFS就能轻松解决的,为何要用BFS? 一般来说,能用DFS解决的问题,都能用BFS. BFS多用于解决最短路问题,其运行过程中需要储存每一层的信息,所以其运行时需要储存的信息量较大,如果人脑也可储存大量信息的话,理论上人脑也可运行BFS. Backtracking相当于在DFS的基础上进行剪枝. 联系 BF…

http://www.lightoj.com/volume_showproblem.php?problem=1027 You are in a maze; seeing n doors in front of you in beginning. You can choose any door you like. The probability for choosing a door is equal for all doors. If you choose the ith door, it ca…

  寻找最可能的隐藏状态序列(Finding most probable sequence of hidden states) 对于一个特殊的隐马尔科夫模型(HMM)及一个相应的观察序列,我们常常希望能找到生成此序列最可能的隐藏状态序列. 1.穷举搜索 我们使用下面这张网格图片来形象化的说明隐藏状态和观察状态之间的关系: 我们可以通过列出所有可能的隐藏状态序列并且计算对于每个组合相应的观察序列的概率来找到最可能的隐藏状态序列.最可能的隐藏状态序列是使下面这个概率最大的组合: Pr(观察序列|隐藏…