[python] 2019-02-27

有点晚。。

973. K Closest Points to Origin

1) Description

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.)

2. Solution

class Solution:
    def kClosest(self, points: List[List[int]], K: int) -> List[List[int]]:
        R=[]
        for res in points:
            R.append(res[0]**2 + res[1]**2)
        R1=R.copy()
        R1.sort()
        p=[]
        for i in range(K):
            p.append(points[R.index(R1[i])])
        return p

other's

class Solution(object):
    def kClosest(self, points, K):
        points.sort(key = lambda P: P[0]**2 + P[1]**2)
        return points[:K]