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Convex Hull | Set 2 (Graham Scan) - GeeksforGeeks
Let points[0..n-1] be the input array.
1) Find the bottom-most point by comparing y coordinate of all points. If there are two points with same y value, then the point with smaller x coordinate value is considered. Put the bottom-most point at first position.
2) Consider the remaining n-1 points and sort them by polor angle in counterclockwise order around points[0]. If polor angle of two points is same, then put the nearest point first.
3) Create an empty stack ‘S’ and push points[0], points[1] and points[2] to S.
4) Process remaining n-3 points one by one. Do following for every point ‘points[i]‘
4.1) Keep removing points from stack while orientation (Link->http://ift.tt/1pEBD4g) of following 3 points is not counterclockwise or they don’t make a left turn.
a) Point next to top in stack
b) Point at the top of stack
c) points[i]
4.2) Push points[i] to S
5) Print contents of S
http://ift.tt/ZpfbqV
http://ift.tt/1pEBBJR
Let points[0..n-1] be the input array.
1) Find the bottom-most point by comparing y coordinate of all points. If there are two points with same y value, then the point with smaller x coordinate value is considered. Put the bottom-most point at first position.
2) Consider the remaining n-1 points and sort them by polor angle in counterclockwise order around points[0]. If polor angle of two points is same, then put the nearest point first.
3) Create an empty stack ‘S’ and push points[0], points[1] and points[2] to S.
4) Process remaining n-3 points one by one. Do following for every point ‘points[i]‘
4.1) Keep removing points from stack while orientation (Link->http://ift.tt/1pEBD4g) of following 3 points is not counterclockwise or they don’t make a left turn.
a) Point next to top in stack
b) Point at the top of stack
c) points[i]
4.2) Push points[i] to S
5) Print contents of S
http://ift.tt/ZpfbqV
http://ift.tt/1pEBBJR
from Public RSS-Feed of Jeffery yuan. Created with the PIXELMECHANICS 'GPlusRSS-Webtool' at http://gplusrss.com http://ift.tt/1pEBD4m
via LifeLong Community
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