记忆化搜索(DFS+DP) URAL 1223 Chernobyl’ Eagle on a Roof

 

题目传送门

 1 /*
 2     记忆化搜索(DFS+DP):dp[x][y] 表示x个蛋,在y楼扔后所需要的实验次数
 3         ans = min (ans, max (dp[x][y-i], dp[x-1][i-1]) + 1);前者表示蛋没碎,则往高处(y-i)搜索
 4             后者表示蛋碎了,往低处(i-1)方向搜索
 5     这样写不好,每次memset (dp)就会超时:(
 6     详细解释:http://blog.csdn.net/fulongxu/article/details/27110435        
 7 */
 8 #include <cstdio>
 9 #include <iostream>
10 #include <algorithm>
11 #include <cstring>
12 #include <cmath>
13 using namespace std;
14 
15 const int MAXN = 1e3 + 10;
16 const int INF = 0x3f3f3f3f;
17 int dp[11][MAXN];
18 
19 int DFS(int x, int y)
20 {
21     if (dp[x][y])    return dp[x][y];
22     if (x == 1)    {dp[x][y] = y;    return y;}
23     if (y <= 2)    {dp[x][y] = y;    return y;}
24 
25     int ans = INF;
26     for (int i=2; i<y; ++i)
27     {
28         int tmp = max (DFS (x, y-i) + 1, DFS (x-1, i-1) + 1);
29         ans = min (ans, tmp);
30     }
31 
32     return dp[x][y] = ans;
33 }
34 
35 int main(void)        //URAL 1223 Chernobyl’ Eagle on a Roof
36 {
37     //freopen ("Z.in", "r", stdin);
38 
39     int n, m;
40     while (scanf ("%d%d", &n, &m) == 2)
41     {
42         if (!n && !m)    break;
43         if (n > 10)    n = 10;
44 
45         printf ("%d\n", DFS (n, m));
46     }
47 
48     return 0;
49 }

 

posted @ 2015-05-12 16:18  Running_Time  阅读(166)  评论(0)    收藏  举报