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],
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    ?

Return true (self crossing)

Example 2:

Given x = [1, 2, 3, 4],
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Return false (not self crossing)

Example 3:

Given x = [1, 1, 1, 1],
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Return true (self crossing)

Credits:
Special thanks to @dietpepsi for adding this problem and creating all test cases.