Given n points on a 2D plane, find the maximum number of points that lie on the same straight line.
Example 1:
Input: [[1,1],[2,2],[3,3]] Output: 3 Explanation: ^ | | o | o | o +-------------> 0 1 2 3 4
Example 2:
Input: [[1,1],[3,2],[5,3],[4,1],[2,3],[1,4]] Output: 4 Explanation: ^ | | o | o o | o | o o +-------------------> 0 1 2 3 4 5 6
给定一个二维平面，平面上有 n 个点，求最多有多少个点在同一条直线上。
示例 1:
输入: [[1,1],[2,2],[3,3]] 输出: 3 解释: ^ | | o | o | o +-------------> 0 1 2 3 4
示例 2:
输入: [[1,1],[3,2],[5,3],[4,1],[2,3],[1,4]] 输出: 4 解释: ^ | | o | o o | o | o o +-------------------> 0 1 2 3 4 5 6
44ms
1 /**
2 * Definition for a point.
3 * public class Point {
4 * public var x: Int
5 * public var y: Int
6 * public init(_ x: Int, _ y: Int) {
7 * self.x = x
8 * self.y = y
9 * }
10 * }
11 */
12 class Solution {
13 func maxPoints(_ points: [Point]) -> Int {
14 var result: Int = 0
15 for i in 0 ..< points.count {
16 var map: [String: Int] = [:]
17 var same: Int = 0
18 var maxP: Int = 0
19 for j in i + 1 ..< points.count {
20 var x = points[j].x - points[i].x
21 var y = points[j].y - points[i].y
22 if x == 0 && y == 0 {
23 // same point
24 same += 1
25 continue
26 }
27 let gcd = findGCD(x, y)
28 if gcd != 0 {
29 x /= gcd
30 y /= gcd
31 }
32 let d = "\(x)@\(y))"
33 map[d, default: 0] += 1
34 maxP = max(maxP, map[d]!)
35 }
36 result = max(result, maxP + same + 1) // 1 for itself
37 }
38 return result
39 }
40
41 func findGCD(_ a: Int, _ b: Int) -> Int {
42 if b == 0 {
43 return a
44 }
45 return findGCD(b, a % b)
46 }
47 }
48ms
1 /**
2 * Definition for a point.
3 * public class Point {
4 * public var x: Int
5 * public var y: Int
6 * public init(_ x: Int, _ y: Int) {
7 * self.x = x
8 * self.y = y
9 * }
10 * }
11 */
12 class Solution {
13 func maxPoints(_ points: [Point]) -> Int {
14 guard points.count > 2 else {
15 return points.count
16 }
17 var result = 0
18 for i in 0..<points.count {
19 var overlap = 0
20 var infinite = 0
21 var zero = 0
22 var tempMax = 0
23 var map = [Int: [Int: Int]]()
24 for j in i + 1..<points.count {
25 var xDiff = points[j].x - points[i].x
26 var yDiff = points[j].y - points[i].y
27 if xDiff == 0 && yDiff == 0 {
28 overlap += 1
29 } else if xDiff == 0 {
30 infinite += 1
31 } else if yDiff == 0 {
32 zero += 1
33 } else {
34 let gcd = getGcd(xDiff, yDiff)
35 xDiff /= gcd
36 yDiff /= gcd
37 if map[xDiff] != nil {
38 map[xDiff]![yDiff] = (map[xDiff]![yDiff] ?? 0) + 1
39 } else {
40 map[xDiff] = [yDiff: 1]
41 }
42 tempMax = max(tempMax, map[xDiff]![yDiff]!)
43 }
44 }
45 result = max(result, max(max(infinite, zero), tempMax) + overlap)
46 }
47 return result + 1
48 }
49
50 private func getGcd(_ a: Int, _ b: Int) -> Int {
51 var a = a
52 var b = b
53 while b != 0 {
54 let temp = b
55 b = a % b
56 a = temp
57 }
58 return a
59 }
60 }
80ms
1 /**
2 * Definition for a point.
3 * public class Point {
4 * public var x: Int
5 * public var y: Int
6 * public init(_ x: Int, _ y: Int) {
7 * self.x = x
8 * self.y = y
9 * }
10 * }
11 */
12 class Solution {
13 func maxPoints(_ points: [Point]) -> Int {
14 guard points.count > 2 else {
15 return points.count
16 }
17 var maxPointsCount = 2
18 for i in 0 ..< points.count {
19 var dict = [P: Int]()
20 var maxCount = 1
21 var vertical = 1
22 var duplicateI = 0
23 for j in 0 ..< points.count {
24 if i != j {
25 if points[i].x == points[j].x, points[i].y == points[j].y {
26 duplicateI += 1
27 } else if points[j].x - points[i].x == 0 {
28 vertical += 1
29 } else {
30 let dy = points[j].y - points[i].y
31 let dx = points[j].x - points[i].x
32 let gcd = getGCD(dx, dy)
33 if let count = dict[P(dy / gcd, dx / gcd)] {
34 dict[P(dy / gcd, dx / gcd)] = count + 1
35 if count + 1 > maxCount {
36 maxCount = count + 1
37 }
38 } else {
39 dict[P(dy / gcd, dx / gcd)] = 2
40 }
41 }
42 }
43 }
44 maxPointsCount = max(maxPointsCount, maxCount + duplicateI, vertical + duplicateI)
45 }
46 return maxPointsCount
47 }
48
49 func getGCD(_ dx: Int, _ dy: Int) -> Int {
50 var x = dx
51 var y = dy
52 while y != 0 {
53 let temp = y
54 y = x % y
55 x = temp
56 }
57 return x
58 }
59 class P: Hashable {
60 let x: Int
61 let y: Int
62 var hashValue: Int {
63 return (x + y).hashValue
64 }
65 init(_ x: Int, _ y: Int) {
66 self.x = x
67 self.y = y
68 }
69 static func == (lhs: P, rhs: P) -> Bool {
70 return lhs.x == rhs.x && lhs.y == rhs.y
71 }
72 }
73 }
88ms
1 /**
2 * Definition for a point.
3 * public class Point {
4 * public var x: Int
5 * public var y: Int
6 * public init(_ x: Int, _ y: Int) {
7 * self.x = x
8 * self.y = y
9 * }
10 * }
11 */
12 class Solution {
13 func maxPoints(_ points: [Point]) -> Int {
14
15 guard points.count > 2 else { return points == nil ? 0: points.count }
16
17 var map: [[Int]: Int] = [[Int]: Int]()
18 var maxPoints = 0
19
20 for i in 0 ..< points.count {
21 map.removeAll()
22
23 var localMax = 0
24 var duplicate = 0
25
26 for j in i + 1 ..< points.count {
27
28 var x = points[j].x - points[i].x
29 var y = points[j].y - points[i].y
30
31 if x == 0 && y == 0 {
32 duplicate += 1
33 continue
34 }
35
36 let gcd = generateGCD(x, y)
37
38 if gcd != 0 {
39 x = x / gcd
40 y = y / gcd
41 }
42
43 if let value = map[[x, y]] {
44 map[[x, y]] = value + 1
45 } else {
46 map[[x, y]] = 1
47 }
48
49 localMax = max(localMax, map[[x, y]]!)
50 }
51
52 maxPoints = max(maxPoints, localMax+duplicate+1)
53 }
54 return maxPoints
55
56 }
57
58 func generateGCD(_ x: Int, _ y: Int) -> Int {
59
60 if y == 0 {
61 return x
62 } else {
63 return generateGCD(y, x % y)
64 }
65 }
66 }
288 ms
1 /**
2 * Definition for a point.
3 * public class Point {
4 * public var x: Int
5 * public var y: Int
6 * public init(_ x: Int, _ y: Int) {
7 * self.x = x
8 * self.y = y
9 * }
10 * }
11 */
12 class Solution {
13 func maxPoints(_ points: [Point]) -> Int {
14 var res:Int = 0
15 var n:Int = points.count
16 for i in 0..<n
17 {
18 var duplicate:Int = 1
19 for j in (i + 1)..<n
20 {
21 var cnt:Int = 0
22 var x1:Int = points[i].x
23 var y1:Int = points[i].y
24 var x2:Int = points[j].x
25 var y2:Int = points[j].y
26 if x1 == x2 && y1 == y2
27 {
28 duplicate += 1
29 continue
30 }
31 for k in 0..<n
32 {
33 var x3:Int = points[k].x
34 var y3:Int = points[k].y
35 if x1*y2 + x2*y3 + x3*y1 - x3*y2 - x2*y1 - x1 * y3 == 0
36 {
37 cnt += 1
38 }
39 }
40 res = max(res, cnt)
41 }
42 res = max(res, duplicate)
43 }
44 return Int(res)
45 }
46 }
原文地址：https://www.cnblogs.com/strengthen/p/10048982.html
时间： 2024-10-08 19:54:45