diff --git a/src/main/java/com/fishercoder/solutions/_149.java b/src/main/java/com/fishercoder/solutions/_149.java index a2be015baf..db70e81d3b 100644 --- a/src/main/java/com/fishercoder/solutions/_149.java +++ b/src/main/java/com/fishercoder/solutions/_149.java @@ -1,95 +1,30 @@ -package com.fishercoder.solutions; +**Updated solution** [credits](https://leetcode.com/problems/max-points-on-a-line/discuss/328269/A-Java-solution-with-my-understanding) -import com.fishercoder.common.classes.Point; -import java.util.HashMap; -import java.util.Map; - -/** - * 149. Max Points on a Line - * - * 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 - * - */ -public class _149 { - - public static class Solution1 { - /** credit: https://leetcode.com/problems/max-points-on-a-line/discuss/47113/A-java-solution-with-notes */ - public int maxPoints(Point[] points) { - if (points == null) { - return 0; - } - if (points.length <= 2) { - return points.length; - } - - Map> map = new HashMap<>(); - int result = 0; - for (int i = 0; i < points.length; i++) { - map.clear(); - int overlap = 0; +class Solution { + public int maxPoints(int[][] points) { + if(points.length < 3)return points.length; int max = 0; - for (int j = i + 1; j < points.length; j++) { - int x = points[j].x - points[i].x; - int y = points[j].y - points[i].y; - if (x == 0 && y == 0) { - overlap++; - continue; - } - int gcd = generateGCD(x, y); - if (gcd != 0) { - x /= gcd; - y /= gcd; - } - - if (map.containsKey(x)) { - if (map.get(x).containsKey(y)) { - map.get(x).put(y, map.get(x).get(y) + 1); - } else { - map.get(x).put(y, 1); + HashMap map = new HashMap(); + for(int i = 0;i < points.length;i++) { + int dup = 1; + map.clear(); + for(int j = i + 1;j < points.length;j++) { + int dx = points[j][0] - points[i][0], dy = points[j][1] - points[i][1]; + if(dx == 0 && dy == 0)dup++; + else { + int gcd = getGcd(dx, dy); + long slope = ((long)(dy / gcd) << 32) + (dx / gcd); + map.put(slope, map.getOrDefault(slope, 0) + 1); + } } - } else { - Map m = new HashMap<>(); - m.put(y, 1); - map.put(x, m); - } - max = Math.max(max, map.get(x).get(y)); + max = Math.max(max, dup); + for(Map.Entry entry : map.entrySet()) + max = Math.max(max, entry.getValue() + dup); } - result = Math.max(result, max + overlap + 1); - } - return result; + return max; } - - private int generateGCD(int a, int b) { - if (b == 0) { - return a; - } else { - return generateGCD(b, a % b); - } + + int getGcd(int a, int b) { + return b == 0 ? a : getGcd(b, a % b); } - } } pFad - Phonifier reborn

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