A sample Hamilton path （经典状压dp，哈密顿路径）

 

Give you a Graph,you have to start at the city with ID zero.

Input

The first line is n(1<=n<=21) m(0<=m<=3) 
The next n line show you the graph, each line has n integers. 
The jth integers means the length to city j.if the number is -1 means there is no way. If i==j the number must be -1.You can assume that the length will not larger than 10000 
Next m lines,each line has two integers a,b (0<=a,b The input end with EOF. 

Output

For each test case,output the shorest length of the hamilton path. 
If you could not find a path, output -1 

Sample Input

3 0
-1 2 4
-1 -1 2
1 3 -1
4 3
-1 2 -1 1
2 -1 2 1
4 3 -1 1
3 2 3 -1
1 3
0 1
2 3

Sample Output

4
5


        
  

Hint

I think that all of you know that a!=b and b!=0    =。=

题意：求从0点开始的最短哈密顿路径，要求某些点必须在某些点之前经过（每个点只走一次，走完所有点）

思路：状压dp，dp[sta][end]表示已经走过的点的集合状态是sta，走过的最后一个点是end 的最短距离

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