Score : 700 points
You are given a string s of length n. Does a tree with n vertices that satisfies the following conditions exist?
1
, we can have a connected component of size i by removing one edge from the tree.0
, we cannot have a connected component of size i by removing any one edge from the tree.If such a tree exists, construct one such tree.
0
and 1
.Input is given from Standard Input in the following format:
s
If a tree with n vertices that satisfies the conditions does not exist, print -1
.
If a tree with n vertices that satisfies the conditions exist, print n-1 lines. The i-th line should contain u_i and v_i with a space in between. If there are multiple trees that satisfy the conditions, any such tree will be accepted.
1111
-1
It is impossible to have a connected component of size n after removing one edge from a tree with n vertices.
1110
1 2 2 3 3 4
If Edge 1 or Edge 3 is removed, we will have a connected component of size 1 and another of size 3. If Edge 2 is removed, we will have two connected components, each of size 2.
1010
1 2 1 3 1 4
Removing any edge will result in a connected component of size 1 and another of size 3.