Max Points on a Line
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这道题做不出来的原因是，斜率不会比较（精度问题）。
下面的代码是网上的方法，用的是unordered_map，相当于一个hash索引，所以不会有精度问题。
过些天再做这个题，看能不能扁出来
/** * Definition for a point. * struct Point { * int x; * int y; * Point() : x(0), y(0) {} * Point(int a, int b) : x(a), y(b) {} * }; */class Solution {public: int maxPoints(vector<Point> &points) { // IMPORTANT: Please reset any member data you declared, as // the same Solution instance will be reused for each test case. int len = points.size(), res = 1; if(len == 0)return 0; unordered_map<double, int> umap; for(int i = 0; i < len; i++) { umap.clear(); int samePointNum = 0,tmpres = 1; for(int j = i+1; j < len; j++) { double slope = std::numeric_limits<double>::infinity();//斜率 if(points[i].x != points[j].x) slope = 1.0*(points[i].y - points[j].y) / (points[i].x - points[j].x); else if(points[i].y == points[j].y) {samePointNum++; continue;} int tmp; if(umap.find(slope) != umap.end()) tmp = ++umap[slope]; else { umap.insert(unordered_map<double, int>::value_type(slope, 2)); tmp = 2; } if(tmpres < tmp)tmpres = tmp; } if(res < tmpres + samePointNum)res = tmpres + samePointNum; } return res; }};
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