[LeeCode] 973. K Closest Points to Origin (Python) 最小堆/ 快排_973. k closest points to origin python

973. K Closest Points to Origin

Medium

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. 1 <= K <= points.length <= 10000
2. -10000 < points[i][0] < 10000
3. -10000 < points[i][1] < 10000

 

笔记：

方法1： 快排

class Solution:
    def kClosest(self, points: List[List[int]], K: int) -> List[List[int]]:
        points = sorted(points, key = lambda x: x[0]**2+x[1]**2)
        return points[:K]

 

方法2：最小堆

class Solution:
    def kClosest(self, points: List[List[int]], K: int) -> List[List[int]]:
        dis = []
        for point in points:
            l = point[0]**2 + point[1]**2
            dis.append((l,point))
        return [d[1] for d in heapq.nsmallest(K, dis)]