[LeetCode]Maximum number of points on a straight line in 2d plane

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Solution:

Remember that a line can be represented by y=kx+d, if p1 and p2 are in same line, then y1=x1k+d, y2=kx2+d, so y2-y1=kx2-kx1, so k=(y2-y1)/(x2-x1), then we can apply this formula to check if two points are in same line, however how to handle the duplicate points problem?Remember that a li