hdu 5612 Baby Ming and Matrix games

Posted 2020-06-08

题目链接：http://acm.hdu.edu.cn/showproblem.php?pid=5612

题意：给出一个矩阵，在（i*2，j*2）（i，j = 0, 1, 2...）是数字0-9，数字之间是+，-，*，/运算符。其他位置是#号。

问给出一个数字，有没有可能在矩阵中找到一条路线可以计算得到这个数字。

思路：DFS搜索

 1 #include <bits/stdc++.h>
 2 using namespace std;
 3 char mp[35][35];
 4 int T;
 5 int vis[35][35];
 6 int n, m;
 7 double sum;
 8 #define eps 1e-10
 9 bool flag;
10 void dfs(int x, int y, double val)
11 {
12     if(flag) return;
13     if(fabs(sum-val) < eps)
14     {
15         flag = true; return;
16     }
17     if(x-2 >= 0)
18     {
19         if(!vis[x-2][y])
20         {
21             vis[x-2][y] = 1;
22             if(mp[x-1][y] == ‘*‘) dfs(x-2, y, val*(mp[x-2][y]-‘0‘));
23             else if(mp[x-1][y] == ‘+‘) dfs(x-2, y, val+(mp[x-2][y]-‘0‘));
24             else if(mp[x-1][y] == ‘-‘) dfs(x-2, y, val-(mp[x-2][y]-‘0‘));
25             else if(mp[x-1][y] == ‘/‘) dfs(x-2, y, val/(mp[x-2][y]-‘0‘));
26             vis[x-2][y] = 0;
27         } 
28     }
29     if(x+2 <= n-1)
30     {
31         if(!vis[x+2][y])
32         {
33             vis[x+2][y] = 1;
34             if(mp[x+1][y] == ‘*‘) dfs(x+2, y, val*(mp[x+2][y]-‘0‘));
35             else if(mp[x+1][y] == ‘+‘) dfs(x+2, y, val+(mp[x+2][y]-‘0‘));
36             else if(mp[x+1][y] == ‘-‘) dfs(x+2, y, val-(mp[x+2][y]-‘0‘));
37             else if(mp[x+1][y] == ‘/‘) dfs(x+2, y, val/(mp[x+2][y]-‘0‘));
38             vis[x+2][y] = 0;
39 
40         }
41     }
42    if(y-2 >= 0)
43     {
44         if(!vis[x][y-2])
45         {
46             vis[x][y-2] = 1;
47             if(mp[x][y-1] == ‘*‘) dfs(x, y-2, val*(mp[x][y-2]-‘0‘));
48             else if(mp[x][y-1] == ‘+‘) dfs(x, y-2, val+(mp[x][y-2]-‘0‘));
49             else if(mp[x][y-1] == ‘-‘) dfs(x, y-2, val-(mp[x][y-2]-‘0‘));
50             else if(mp[x][y-1] == ‘/‘) dfs(x, y-2, val/(mp[x][y-2]-‘0‘));
51             vis[x][y-2] = 0;
52         }
53     }
54     
55     if(y+2 <= m-1)
56     {
57         if(!vis[x][y+2])
58         {
59             vis[x][y+2] = 1;
60             if(mp[x][y+1] == ‘*‘) dfs(x, y+2, val*(mp[x][y+2]-‘0‘));
61             else if(mp[x][y+1] == ‘+‘) dfs(x, y+2, val+(mp[x][y+2]-‘0‘));
62             else if(mp[x][y+1] == ‘-‘) dfs(x, y+2, val-(mp[x][y+2]-‘0‘));
63             else if(mp[x][y+1] == ‘/‘) dfs(x, y+2, val/(mp[x][y+2]-‘0‘));
64             vis[x][y+2] = 0;
65         }
66     }
67     
68     return;
69 
70 }
71 int main()
72 {
73     scanf("%d", &T);
74     while(T--)
75     {
76         scanf("%d%d%lf", &n, &m, &sum);
77         for(int i = 0; i < n; i++)
78         {
79             scanf("%s", mp[i]);
80         }
81 
82         flag = false;
83         for(int i = 0; i < n; i+=2)
84         {
85             for(int j = 0; j < m; j+=2)
86             {
87                 memset(vis, 0, sizeof(vis));
88                 vis[i][j] = 1;
89                 dfs(i, j, mp[i][j]-‘0‘);
90                 if(flag == true) break;
91             }
92             if(flag == true) break;
93         }
94         if(flag) printf("Possible\n");
95         else printf("Impossible\n");
96     }
97     return 0;
98 }