CF1491C Pekora and Trampoline translation

Original title link Luogu link

Have $n$ trampolines are arranged in a row, and each trampoline has an elasticity value$s_i$

At the very beginning of each round, Pekora will choose a trampoline as her starting point (any trampoline can be used as a starting point). When she was on the trampoline $When\; i$ , she will jump to the trampoline$i+s_i$On, and $s_i$Will become $max(1,s_i-1)$ (That is, the elasticity value of the trampoline will be reduced by one every time the trampoline is jumped, until the elasticity value is$1$ ). When she jumped to$When\; n$ trampolines are behind, the round ends.

Now, Pekora wants to put all the $s_i$All become $1.$ Ask the minimum number of rounds to achieve this goal

Input format

There are multiple sets of data in this question

An integer TT in the first line$T$ , indicates the number
of groups of data For each group of data:
an integernn in thefirst line$n$ , said the number of trampolines, the
second line$n$ integers,$s_{1\dots n}$

Output format

Total $T$ line, each line an integer represents the answer to the group of data

Instructions and tips

$1\le T\le 500$
$\sum n\le 5000$
$1\le s_i\le 10^9$