题目：

题解：

class Solution {public int maxPoints(int[][] points) {int n = points.length;if (n <= 2) {return n;}int ret = 0;for (int i = 0; i < n; i++) {if (ret >= n - i || ret > n / 2) {break;}Map<Integer, Integer> map = new HashMap<Integer, Integer>();for (int j = i + 1; j < n; j++) {int x = points[i][0] - points[j][0];int y = points[i][1] - points[j][1];if (x == 0) {y = 1;} else if (y == 0) {x = 1;} else {if (y < 0) {x = -x;y = -y;}int gcdXY = gcd(Math.abs(x), Math.abs(y));x /= gcdXY;y /= gcdXY;}int key = y + x * 20001;map.put(key, map.getOrDefault(key, 0) + 1);}int maxn = 0;for (Map.Entry<Integer, Integer> entry: map.entrySet()) {int num = entry.getValue();maxn = Math.max(maxn, num + 1);}ret = Math.max(ret, maxn);}return ret;}public int gcd(int a, int b) {return b != 0 ? gcd(b, a % b) : a;}
}