T1
Total loss compression
First read all the strings, and according to the length from small to large, then a a compressed (a, b, c, ..., z, aa, ab ... this way)
T2
An outward tree (refer to from all sides root out), plus a side, let him find out this edge number as large as possible
discuss
1. Who knows the root to see if there is a 0-degree point
Edges and lateral fork side throwback
Is actually a case, the point is to have a degree of 2
Border Erase twice to see even violence is not connected (directly greedy but I took the biggest, then 100à80)
2. the degree can not find a certain point a cycloalkyl à 0
Remove any one on this side of the ring can be
How to find the ring? BFS, disjoint-set, tarjan
T3
First, k in fact there is no difference
N = 10, k = 5 and n = 2, k = 1 is the same as
Coming into the read n n / k (on rounding), k becomes 1
Give you a number, I asked a number of additional
By meter? ? ?
1. Burst search
Memory can be added of f [i] [j] indicates there are a i, b j is the probability that there are many
Finally seeking f [n] [n]
F[0][j]=1,f[i][0]=0,f[0][0]=0.5
转移 f[i][j]=0.25*(f[i-4][j]+f[i-3][j-1]+f[i-2][j-2]+f[i-1][j-1) 70pts
Complexity n ^ 2
Playing table: n grows, the probability is growing
There are: The answer is only required to retain six decimal places
So, when n>? Only when the output of 1.000000? ? ? ? ? ?
What metaphysics thing? ? ? ?