原题地址：https://oj.leetcode.com/problems/max-points-on-a-line/
题意：Given n points on a 2D plane, find the maximum number of points that lie on the same straight line.
解题思路：找到平面上在一条直线上最多的点。点在同一条直线上意味着这些点的斜率是一样的，那么可以考虑使用哈希表来解决，{斜率：[点1，点2]}这样的映射关系。这里有几个需要考虑的要点：1，有可能是斜率无穷大。2，有可能有相同的点，比如[(1,2),(1,2)]。
代码：
# Definition for a point # class Point: # def __init__(self, a=0, b=0): # self.x = a # self.y = b class Solution: # @param points, a list of Points # @return an integer def maxPoints(self, points): length = len(points) if length < 3: return length res = -1 for i in range(length): slope = {‘inf‘: 0} samePointsNum = 1 for j in range(length): if i == j: continue elif points[i].x == points[j].x and points[i].y != points[j].y: slope[‘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 slope: slope[k] = 1 else: slope[k] += 1 else: samePointsNum += 1 res = max(res, max(slope.values()) + samePointsNum) return res
[leetcode]Max Points on a Line @ Python,布布扣,bubuko.com
[leetcode]Max Points on a Line @ Python
原文：http://www.cnblogs.com/zuoyuan/p/3760628.html