Max Points on a Line

 1 class Solution {
 2 public:
 3     int maxPoints(vector<Point> &points) {
 4         map<double, int> result;
 5         int max_line = 0;
 6         double gradient;//斜率
 7         int multi = 0;
 8         for (vector<Point>::iterator ix = points.begin(); ix != points.end(); ++ix) {
 9             result.clear();
10             multi = 1;
11             result[INT_MIN] = 0;
12             for (vector<Point>::iterator jx = points.begin(); jx != points.end(); ++jx) {
13                 if (ix == jx) {
14                     continue;
15                 }
16                 if(ix->x == jx->x && ix->y == jx->y){
17                     ++multi;
18                     continue;
19                 }
20                 if(ix->x != jx->x){
21                     gradient = (double)(ix->y - jx->y) / (ix->x - jx->x);
22                     result[gradient]++;
23                 }else{
24                     result[INT_MAX]++;
25                 }
26             }
27             for (map<double, int>::iterator ix = result.begin(); ix != result.end(); ++ix){
28                 if (ix->second + multi > max_line) {
29                     max_line = ix->second + multi;
30                 }
31             }
32         }
33         return max_line;
34     }
35 };