[LeetCode OJ] Max Points on a Line

Max Points on a Line

Submission Details

27 / 27 test cases passed.	Status:  Accepted
Runtime:  472 ms	Submitted:  0 minutes ago

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Submitted Code

Language:  java

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 1 /**

 2  * Definition for a point.

 3  * class Point {

 4  *     int x;

 5  *     int y;

 6  *     Point() { x = 0; y = 0; }

 7  *     Point(int a, int b) { x = a; y = b; }

 8  * }

 9  */

10 import java.util.HashMap;

11 import java.util.Map;

12  

13  

14 public class Solution {

15     public int maxPoints(Point[] points) {

16         if (points == null || points.length == 0)

17             return 0;

18         int N = points.length;

19         if (N == 1)

20             return 1;

21         if (N == 2)

22             return 2;

23  

24         Map<String, Integer> dict = new HashMap<String, Integer>();

25         int maxOverall = 0;

26         for (int i = 0; i < N - 1; i++) {

27             int same = 1;

28             int max = 0;

29             for (int j = i + 1; j < N; j++) {

30  

31                 int p1x = points[i].x;

32                 int p1y = points[i].y;

33                 int p2x = points[j].x;

34                 int p2y = points[j].y;

35  

36                 if (p1x == p2x && p1y == p2y) {

37                     same++;

38                     continue;

39                 }

40  

41                 int A = p2y - p1y;

42                 int B = p1x - p2x;

43  

44                 int GCD = gcd(A, B);

45                 if (GCD != 0 && GCD != 1) {

46                     A /= GCD;

47                     B /= GCD;

48                 }

49                 if (A < 0) {

50                     A = -A;

51                     B = -B;

52                 }

53  

54                 String key = A + "," + B;

55 //              System.out.println("round:" + i + " " + key);

56                 int value = 1;

57                 if (dict.containsKey(key)) {

58                     value += dict.get(key);

59                 } 

60                 dict.put(key, value);

61                 max = max < value  ? value  : max;

62             }

63             

64             max += same;

65             maxOverall = maxOverall < max ? max : maxOverall;

66             dict.clear();

67         }

68  

69         return maxOverall;

70     }

71  

72     public int gcd(int a, int b) {

73         if (b == 0)

74             return a;

75         return gcd(b, a % b);

76     }

77 }

78  

 

 

 

 

 

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