POJ 3050 Hopscotch

http://poj.org/problem?id=3050

深搜 + set去重

这道题的深搜很简单每满六次后 insertin进set即可最终果就是set.size()

 1 #include <iostream>
 2 #include <fstream>
 3 #include <stdio.h>
 4 #include <string>
 5 #include <set>
 6 
 7 using namespace std;
 8 
 9 string srec;
10 char rec[8];
11 int d[4][2] = { {-1,0}, {0, 1}, {1, 0}, {0, -1} };
12 int grid[8][8];
13 
14 set<string> str_set;
15 
16 bool check(int x, int y)
17 {
18     if (x < 0 || y < 0 || x >= 5 || y >= 5) return false;
19     return true;
20 }
21 
22 void dfs(int x, int y, int n)//深搜的话 O(n^2*4^5*nlogn) --->>> 25*4^5*nlogn 数据小还好 用set消重
23 {
24     if (n == 6)
25     {
26         srec = rec;
27         str_set.insert(srec);
28         return ;
29     }
30     rec[n] = grid[x][y] + '0';//记录这个格子里的数
31     for (int i = 0; i < 4; i++)
32     {
33         if (check(x+d[i][0], y+d[i][1]))//越界检查
34         {
35             dfs(x+d[i][0], y+d[i][1], n+1);
36         }
37     }
38 }
39 
40 int main()
41 {
42     freopen("in.txt", "r", stdin);
43     ofstream cout ("out.txt");
44     for (int i = 0; i < 5; i++)
45     {
46         for (int j = 0;j < 5; j++)
47         {
48             scanf("%d", &grid[i][j]);
49         }
50     }
51     for (int i = 0; i < 5; i++)
52     {
53         for (int j = 0; j < 5; j++)
54         {
55             dfs(i,j,0);
56         }
57     }
58     printf("%d", str_set.size());
59     return 0;
60 }