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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? ?
?
?
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Return false (not self crossing)
Example 3:
Given x = [1, 1, 1, 1]
,
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? ?
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Return true (self crossing)
Credits:
Special thanks to @dietpepsi for adding this problem and creating all test cases.
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