[Leetcode]149. Max Points on a Line @python

题目

Given n points on a 2D plane, find the maximum number of points that lie on the same straight line.

题目要求

给定n个2维平面上的点，找到在同一直线上最多的点数。

解题思路

在同一直线上要求所有点的斜率相同且经过同一个点。同时要考虑，斜率可能为无穷大，也有可能两个点为同一个点。

代码

# Definition for a point.
# class Point(object):
#     def __init__(self, a=0, b=0):
#         self.x = a
#         self.y = b

class Solution(object):
def maxPoints(self, points):
"""
:type points: List[Point]
:rtype: int
"""
length = len(points)
if length < 3: return length
max_points = 0
for i in range(length):
maps = {'inf':0}
same = 1
for j in range(i,length):
if i == j:
continue
if points[i].x == points[j].x and points[i].y != points[j].y:
maps['inf'] += 1
elif points[i].x != points[j].x:
k = 1.0 * (points[i].y - points[j].y) / (points[i].x - points[j].x)
if k not in maps:
maps[k] = 1
else:
maps[k] += 1
else:
same += 1
max_points = max(max_points,max(maps.values()) + same)
return max_points