345. Is There a Path Adding to T
Print Yes if some root-to-leaf path has values totalling exactly t, and
No otherwise.
The path must run from the root all the way to a LEAF. A partial path that
happens to reach t part way down does not count, and neither does a path
between two nodes that avoids the root.
Carry the running total down and compare it with t only on arrival at a leaf.
Values may be negative, so you cannot abandon a branch merely because the total
has already passed t.
Constraints - `1 ≤ n ≤ 100000` - `-1000000000000000 ≤ t ≤ 1000000000000000` - `-1000000000 ≤ value ≤ 1000000000` - The input always forms a valid tree rooted at node 1.
Input
The first line contains two integers n and t.
The second line contains n values, where node i holds the ith value.
Each of the next n lines contains the left and right child of node i,
using 0 for no child. Node 1 is the root.
Output
Print Yes or No on one line.
Hints
Four rungs, in order. The last two open once you have submitted an attempt. A wrong one counts.