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: Given x = [2, 1, 1, 2], ┌───┐ │ │ └───┼──> │
Return true (self crossing) Example 2: Given x = [1, 2, 3, 4], ┌──────┐ │ │ │ │ └────────────>
Return false (not self crossing) Example 3: Given x = [1, 1, 1, 1], ┌───┐ │ │ └───┼>
Return true (self crossing)