You are given an array x of n positive numbers. You start at point (0,0)
and moves x[0] metres to the north, then x[1] metres to the west,
x[2] metres to the south, x[3] metres to the east and so on. In
other words, after each move your direction changes counter-clockwise.
Write a one-pass algorithm with O(1) extra space to determine, if your path
crosses itself, or not.
Example 1:
┌───┐
│ │
└───┼──>
│
Input: [2,1,1,2]
Output: true
Example 2:
┌──────┐
│ │
│
│
└────────────>
Input: [1,2,3,4]
Output: false
Example 3:
┌───┐
│ │
└───┼>
Input: [1,1,1,1]
Output: true