HDU 2605 Snake（DFS+BFS+技巧+细节）（好题）

Snake

Time Limit: 10000/6000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 222    Accepted Submission(s): 45

Problem Description

Snake is a popular game , and I believe most of us had played it . The Original game is that you can control a snake to eat the magic bean and after the snake eat one magic bean , the length of the snake’s body will get longer .But today we are talking about a new game. These are the rules of the new Snake Game :
1. The length of the snake’s body won’t change even though it eat a magic bean.
2. Some pairs of the beans have a relation , that is, one of them can not be eaten until another one had been eaten . We call the latter “the key bean” . For example , if A can’t be eaten until B had been eaten ,we say “B is the key bean of A”. (That means when A can’t be eaten , the snake can not move into the grid where A is.)
3. The snake could not move to a wall or its body.Befor it move,it will chooses an adjacent vacant square of its head,which is neither a stone nor occupied by its body.
Figure 1 and figure2 shows how the snake move

Figure 1

Figure 2

Input

The first line contain a integer T (T <= 10).Followed by T cases. Each case contain five parts.
The first part: six integers ,H,W,L,K,R,N,(H <= 20 , W <= 20 , L <= 8 , K <= 7 ) means the height of the map , the width of the map , the length of the snake’s body, the number of the magic beans . the number of the relations , the number of the wall respectively.
The second part: L lines , each line contain two integer h_i ,w_i, indicating the original position of each block of snake's body, from B₁(h₁,w₁) to B_L(h_L,w_L) orderly, where 1<=h_i<=H, and 1<=w_i<=W,1<=i<=L.
The third part: K lines ,each line contain two integer h_i ,w_i , indicating the position of each magic bean , from MB₁(h₁,w₁) to MB_K(h_K,w_K) orderly, where 1<=h_i<=H, and 1<=w_i<=W,1<=i<=K.
The fourth part : R lines , each line contain two integer A ,B means “A is the key bean of B ”. The A and B may appear several times , but “one bean will have only one key bean”.
The fifth part: N lines , each line contain two integer h_i ,w_i , indicating the position of each wall , from W₁(h₁,w₁) to W_N(h_N,w_N) orderly, where 1<=h_i<=H, and 1<=w_i<=W,1<=i<=N. 

Output

For each case , if the snake could eat all the magic beans , output the minimum step it took. If the snake could not , just output “-1” (without the quotation marks) .

 

Sample Input

18 95 21 85 26 26 36 46 54 22 62 12 53 54 44 54 65 65 76 7

Sample Output

21

 

Author

Teddy

 

Source

HDU 1st “Vegetable-Birds Cup” Programming Open Contest

题目链接：

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题解：

这是个好题啊。贪食蛇。爆搜。

注意一下一些细节和技巧就可以。

可能需要你花很多时间慢慢写....

反正我写了一个晚上....

很考验自己的的代码能力，我写了7K...300+行...

注意：

豆子也要成环...dfs判断一下即可。

然后再BFS，判断是否越界或者撞墙，还要判断豆子能不能吃。还要判断蛇头不能碰到自己。

注意MLE，利用一下位运算就可以了。用bitset大法应该也是可以的。