100 doors Toggle Puzzle
Given 100 doors, all are closed initially, with each iteration, the current state of the door will be reversed or toggled, ie if the door is closed then it will be opened and if open then will be closed. The door visited will be dependent if it's multiple of the current iteration.
For example in 1st iteration, all the doors will be visited (#1, #2, #3, #4, #5), in 2nd iteration only multiple of 2 doors (#2, #4, #6, #8, #10) will be visited, in 3rd iteration all the multiple of 3 doors (#3, #6, #9, #12, #15) will be visited and so on.
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