POJ 2488-A Knight's Journey(DFS)
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A Knight‘s Journey
Time Limit: 1000MS | Memory Limit: 65536K | |
Total Submissions: 31702 | Accepted: 10813 |
Description
Background
The knight is getting bored of seeing the same black and white squares again and again and has decided to make a journey
around the world. Whenever a knight moves, it is two squares in one direction and one square perpendicular to this. The world of a knight is the chessboard he is living on. Our knight lives on a chessboard that has a smaller area than a regular 8 * 8 board, but it is still rectangular. Can you help this adventurous knight to make travel plans?
The knight is getting bored of seeing the same black and white squares again and again and has decided to make a journey
around the world. Whenever a knight moves, it is two squares in one direction and one square perpendicular to this. The world of a knight is the chessboard he is living on. Our knight lives on a chessboard that has a smaller area than a regular 8 * 8 board, but it is still rectangular. Can you help this adventurous knight to make travel plans?
Problem
Find a path such that the knight visits every square once. The knight can start and end on any square of the board.
Input
The input begins with a positive integer n in the first line. The following lines contain n test cases. Each test case consists of a single line with two positive integers p and q, such that 1 <= p * q <= 26. This represents a p * q chessboard, where p describes
how many different square numbers 1, . . . , p exist, q describes how many different square letters exist. These are the first q letters of the Latin alphabet: A, . . .
Output
The output for every scenario begins with a line containing "Scenario #i:", where i is the number of the scenario starting at 1. Then print a single line containing the lexicographically first path that visits all squares
of the chessboard with knight moves followed by an empty line. The path should be given on a single line by concatenating the names of the visited squares. Each square name consists of a capital letter followed by a number.
If no such path exist, you should output impossible on a single line.
If no such path exist, you should output impossible on a single line.
Sample Input
3 1 1 2 3 4 3
Sample Output
Scenario #1: A1 Scenario #2: impossible Scenario #3: A1B3C1A2B4C2A3B1C3A4B2C4
题意:国际象棋。然后给一个马(马走日) ,能够从随意点出发,找一条能够訪问全部格子(p*q的棋盘)的路径,注意路径假设有多条要求输出字典序最小的那条。。
然后这个能够搜索的时候按字典序搜。
。
就是搜索方向要固定。。不能随意写了
然后其它的没什么了 直接深搜。搜到答案之后直接return ;
#include <algorithm> #include <iostream> #include <cstring> #include <cstdlib> #include <string> #include <cctype> #include <vector> #include <cstdio> #include <cmath> #include <deque> #include <stack> #include <map> #include <set> #define ll long long #define maxn 116 #define pp pair<int,int> #define INF 0x3f3f3f3f #define max(x,y) ( ((x) > (y)) ? (x) : (y) ) #define min(x,y) ( ((x) > (y)) ? (y) : (x) ) using namespace std; int n,m,k,ans,dir[8][2]={{-1,-2},{1,-2},{-2,-1},{2,-1},{-2,1},{2,1},{-1,2},{1,2}}; bool vis[27][27]; int sx[30],sy[30],top,ok; void dfs(int x,int y) { if(ok) return ; if(top==n*m) { ok=1; for(int i=0;i<top;i++) printf("%c%d",'A'+sy[i]-1,sx[i]); return ; } for(int i=0;i<8;i++) { int tx=x+dir[i][0]; int ty=y+dir[i][1]; if(tx>=1&&tx<=n&&ty>=1&&ty<=m&&!vis[tx][ty]) { vis[tx][ty]=1;sx[top]=tx;sy[top++]=ty; dfs(tx,ty); vis[tx][ty]=0;top--; } } } int main() { int T,cas=1; scanf("%d",&T); while(T--) { scanf("%d%d",&n,&m);ok=0; printf("Scenario #%d:\n",cas++); memset(vis,0,sizeof(vis));top=0; vis[1][1]=1;sx[top]=1;sy[top++]=1; dfs(1,1); if(!ok) printf("impossible"); puts("");if(T)puts(""); } return 0; }
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POJ 2488:A Knight's Journey