Preparando MOJI
There are $$$n$$$ equidistant antennas on a line, numbered from $$$1$$$ to $$$n$$$. Each antenna has a power rating, the power of the $$$i$$$-th antenna is $$$p_i$$$.
The $$$i$$$-th and the $$$j$$$-th antenna can communicate directly if and only if their distance is at most the minimum of their powers, i.e., $$$|i-j| \leq \min(p_i, p_j)$$$. Sending a message directly between two such antennas takes $$$1$$$ second.
What is the minimum amount of time necessary to send a message from antenna $$$a$$$ to antenna $$$b$$$, possibly using other antennas as relays?
Each test contains multiple test cases. The first line contains an integer $$$t$$$ ($$$1\le t\le 100\,000$$$) — the number of test cases. The descriptions of the $$$t$$$ test cases follow.
The first line of each test case contains three integers $$$n$$$, $$$a$$$, $$$b$$$ ($$$1 \leq a, b \leq n \leq 200\,000$$$) — the number of antennas, and the origin and target antenna.
The second line contains $$$n$$$ integers $$$p_1, p_2, \dots, p_n$$$ ($$$1 \leq p_i \leq n$$$) — the powers of the antennas.
The sum of the values of $$$n$$$ over all test cases does not exceed $$$200\,000$$$.
For each test case, print the number of seconds needed to trasmit a message from $$$a$$$ to $$$b$$$. It can be shown that under the problem constraints, it is always possible to send such a message.
310 2 94 1 1 1 5 1 1 1 1 51 1 113 1 33 3 1
4 0 2
In the first test case, we must send a message from antenna $$$2$$$ to antenna $$$9$$$. A sequence of communications requiring $$$4$$$ seconds, which is the minimum possible amount of time, is the following: