We have a list of points on the plane. Find the K closest points to the origin (0, 0).
(Here, the distance between two points on a plane is the Euclidean distance.)
You may return the answer in any order. The answer is guaranteed to be unique (except for the order that it is in.)
Example 1:
Input: points = [[1,3],[-2,2]], K = 1
Output: [[-2,2]]
Explanation:
The distance between (1, 3) and the origin is sqrt(10).
The distance between (-2, 2) and the origin is sqrt(8).
Since sqrt(8) < sqrt(10), (-2, 2) is closer to the origin.
We only want the closest K = 1 points from the origin, so the answer is just [[-2,2]].
Example 2:
Input: points = [[3,3],[5,-1],[-2,4]], K = 2
Output: [[3,3],[-2,4]]
(The answer [[-2,4],[3,3]] would also be accepted.)
Note:
1 <= K <= points.length <= 10000-10000 < points[i][0] < 10000-10000 < points[i][1] < 10000class Solution { public int[][] kClosest(int[][] points, int k) { Map<Double, List<int[]>> map = new HashMap(); for(int[] arr: points){ double kk = help(arr); if(!map.containsKey(kk)){ map.put(kk, new ArrayList()); } map.get(kk).add(arr); } List<Integer> ks = new ArrayList(map.keySet()); Collections.sort(ks); int[][] res = new int[k][2]; List<int[]> list = new ArrayList(); for(int i = 0; i < ks.size(); i++){ int t = map.get(ks.get(i)).size(); for(int j = 0; j < t; j++) list.add(map.get(ks.get(i)).get(j)); } for(int i = 0; i < k; i++) res[i] = list.get(i); return res; } public double help(int[] point){ return Math.sqrt(point[0]*point[0] + point[1]*point[1]); } }
哎 我咋老走弯路
class Solution { public int[][] kClosest(int[][] points, int K) { int N = points.length; int[] dists = new int[N]; for (int i = 0; i < N; ++i) dists[i] = dist(points[i]); Arrays.sort(dists); int distK = dists[K-1]; int[][] ans = new int[K][2]; int t = 0; for (int i = 0; i < N; ++i) if (dist(points[i]) <= distK) ans[t++] = points[i]; return ans; } public int dist(int[] point) { return point[0] * point[0] + point[1] * point[1]; } }
同样的排序方法
973. K Closest Points to Origin
原文：https://www.cnblogs.com/wentiliangkaihua/p/12996293.html