Codeforces Round 783 (Div. 1) |
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Finished |
You are given an array $$$a$$$ consisting of $$$n$$$ positive integers, and an array $$$b$$$, with length $$$n$$$. Initially $$$b_i=0$$$ for each $$$1 \leq i \leq n$$$.
In one move you can choose an integer $$$i$$$ ($$$1 \leq i \leq n$$$), and add $$$a_i$$$ to $$$b_i$$$ or subtract $$$a_i$$$ from $$$b_i$$$. What is the minimum number of moves needed to make $$$b$$$ increasing (that is, every element is strictly greater than every element before it)?
The first line contains a single integer $$$n$$$ ($$$2 \leq n \leq 5000$$$).
The second line contains $$$n$$$ integers, $$$a_1$$$, $$$a_2$$$, ..., $$$a_n$$$ ($$$1 \leq a_i \leq 10^9$$$) — the elements of the array $$$a$$$.
Print a single integer, the minimum number of moves to make $$$b$$$ increasing.
5 1 2 3 4 5
4
7 1 2 1 2 1 2 1
10
8 1 8 2 7 3 6 4 5
16
Example $$$1$$$: you can subtract $$$a_1$$$ from $$$b_1$$$, and add $$$a_3$$$, $$$a_4$$$, and $$$a_5$$$ to $$$b_3$$$, $$$b_4$$$, and $$$b_5$$$ respectively. The final array will be [$$$-1$$$, $$$0$$$, $$$3$$$, $$$4$$$, $$$5$$$] after $$$4$$$ moves.
Example $$$2$$$: you can reach [$$$-3$$$, $$$-2$$$, $$$-1$$$, $$$0$$$, $$$1$$$, $$$2$$$, $$$3$$$] in $$$10$$$ moves.
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