Drunken Knight

Consider a non-empty list of positive int where each number represents a position in the same list. Let’s define a “jump” from position i over a list L as moving to the position L[i]. Thus, jumping over a list L from a given initial position i0 is doing jumps starting at i0 until it jumps outside the range of L or enters a neverending loop.

For example, given the list l = [4, 2, 0, 1] and initial position 3 the jumping will do the following sequence: 3, 1, 2, 0, 4. If the list was l = [3, 2, 0, 1] it would the neverending sequence 3, 1, 2, 0, 3, 1, 2, …

Write the following function in the module with the same name (file drunken_knight.py):

drunken_knight(L, i0)

such that given

• L non-empty list of positive int

• i0 int

modifies L by assigning the value -1 to all positions traversed by jumping over L from the initial position i0 until it jumps on a position whose value has already been changed to -1 (or it jumps outside the range of L).

Per exemple:

>>> l = [3, 2, 0, 1]
>>> drunken_knight(l, 3)
>>> l == [-1,-1,-1,-1]
True

>>> l = [1, 2, 3, 4]
>>> drunken_knight(l, 0)
>>> l == [-1,-1,-1,-1]
True

>>> l = [2, 3, 4, 3, 0]
>>> drunken_knight(l, 2)
>>> l == [-1, 3, -1, 3, -1]
True

Disposes de doctests al fitxer drunken_knight-test.txt.