题目描述 Consider an N x N (1 <= N <= 100) square field composed of 1 by 1 tiles. Some of these tiles are impassible by cows and are marked with an 'x' in this 5 by 5 field that is challenging to navigate: . . B x . . x x A . . . . x . . x . . . . . x .…

P1649 [USACO07OCT]障碍路线Obstacle Course bfs 直接上个bfs 注意luogu的题目和bzoj有不同(bzoj保证有解,还有输入格式不同). #include<iostream> #include<cstdio> #include<cstring> #include<queue> using namespace std; #define pi pair<int,int> #define mkp make_pai…

P1649 [USACO07OCT]障碍路线Obstacle Course 题目描述 Consider an N x N (1 <= N <= 100) square field composed of 1 by 1 tiles. Some of these tiles are impassible by cows and are marked with an 'x' in this 5 by 5 field that is challenging to navigate: . . B x .…

题目描述 Consider an N x N (1 <= N <= 100) square field composed of 1 by 1 tiles. Some of these tiles are impassible by cows and are marked with an 'x' in this 5 by 5 field that is challenging to navigate: . . B x . . x x A . . . . x . . x . . . . . x .…

题目描述 Consider an N x N (1 <= N <= 100) square field composed of 1 by 1 tiles. Some of these tiles are impassible by cows and are marked with an 'x' in this 5 by 5 field that is challenging to navigate: . . B x . . x x A . . . . x . . x . . . . . x .…

题目描述 Consider an N x N (1 <= N <= 100) square field composed of 1 by 1 tiles. Some of these tiles are impassible by cows and are marked with an 'x' in this 5 by 5 field that is challenging to navigate: . . B x . . x x A . . . . x . . x . . . . . x .…

P1649 [USACO07OCT]障碍路线Obstacle Course 裸的dfs,今天学了一个新招,就是在过程中进行最优性减枝. #include<bits/stdc++.h> using namespace std; ; ][]; ][]; ,,,}; ,,,-}; ][]; void dfs(int nx,int ny,int dir,int num) { ||ny>n||ny<||vis[nx][ny]||ans==) return; if(a[nx][ny]=='x'…

题意 给出n* n 的图,A为起点,B为终点,* 为障碍,.可以行走,问最少需要拐90度的弯多少次,无法到达输出-1. 解析 思路:构造N * M * 4个点,即将原图的每个点分裂成4个点.其中点(i,j,k)表示在(i,j)时人的方向是k,然后对于两个点(i,j,k)和(i,j,kk),如果k和kk是两个旋转90度能转换的方向,就连一条边权为1的边,而对于(i,j,k)和(i+dx[ k],j+dy[k],k)连一条边权为0的边,表示从(i,j)在方向为k的情况下能向k方向走一步到达(i+dx…

2021.10.29 P1649 [USACO07OCT]Obstacle Course S(BFS) 题意: 给一张n*n的图,起点为A,终点为 B,求从A到B转弯次数最少为多少. 分析: 是否存在路径用DFS,最短路径或最长路径用BFS.只不过先现在需要把以前距离小的放前面改为转弯次数少的放前面,类似于最短路 . 代码如下: #include<cstdio> #include<iostream> #include<algorithm> #include<cst…

题目链接:https://www.luogu.org/problem/show?pid=1649 历经千辛万苦,我总算是把这个水题AC了,现在心里总觉得一万只草泥马在奔腾: 这是一道很明显的BFS,然后我也明显的看出来了 但是,我就是WA了很久很久,在调试第一个晚上后,我发现读入是存在空格的,而不是数据问题 然后第二个问题就是,BFS找到的第一个终点不一定就是最优的答案(当然第二个问题是我重新打了一次猛然发现之前没注意的一点) 注意到这两点,其实这道题就没难度了 然后这道题的处理需要注意一个地方…