HERE IS THE QUESTION, WHAT IS THE LOGIC AND CODE TO SOLVE THIS QUESTION ??
You are given a maze with N cells. Each cell may have multiple entry points but not more than one exit (ie. entry/exit points are unidirectional doors like valves).

The cells are named with an integer value from 0 to N-1.

You need to find the the length of the largest cycle in the maze. Return -1 if there are no cycles.

INPUT FORMAT

First line has the number of cells N
Second line has list of N values of the edge[] array. edge[i] contains the cell number that can be reached from of cell ‘i’ in one step. edge[i] is -1 if the ‘i’th cell doesn’t have an exit.
OUTPUT FORMAT

length of the largest cycle.
Sample input:

23

4 4 1 4 13 8 8 8 0 8 14 9 15 11 -1 10 15 22 22 22 22 22 21

Sample output

6