973_K_Closest_Points_to_Origin

qiyuangong · qiyuangong · commit 08e37c4c8ccc · 2019-06-26T17:34:44.000+08:00
diff --git a/README.md b/README.md
@@ -209,6 +209,7 @@ Also, there are open source implementations for basic data structs and algorithm
 | 961 | [N-Repeated Element in Size 2N Array](https://leetcode.com/problems/n-repeated-element-in-size-2n-array/submissions/) | [Python](https://github.com/qiyuangong/leetcode/blob/master/python/961_N-Repeated_Element_in_Size_2N_Array.py) [Java](https://github.com/qiyuangong/leetcode/blob/master/java/961_N-Repeated_Element_in_Size_2N_Array.java) | Hash and count number, O(n) and O(n) |
 | 962 | [Maximum Width Ramp](https://leetcode.com/problems/maximum-width-ramp/) | [Python](https://github.com/qiyuangong/leetcode/blob/master/python/962_Maximum_Width_Ramp.py) [Java](https://github.com/qiyuangong/leetcode/blob/master/java/962_Maximum_Width_Ramp.java) | 1. Sort index by value, then transfer problem into finding max gap between index, O(nlogn) and O(1)<br>2. Binary Search for candicates, O(nlogn) and O(n) |
 | 977 | [Squares of a Sorted Array](https://leetcode.com/problems/squares-of-a-sorted-array/) | [Python](https://github.com/qiyuangong/leetcode/blob/master/python/977_Squares_of_a_Sorted_Array.py) [Java](https://github.com/qiyuangong/leetcode/blob/master/java/977_Squares_of_a_Sorted_Array.java) | 1. Sort, O(nlogn) and O(n)<br>2. Two point, O(n) and O(n) |
+| 973 | [K Closest Points to Origin](https://leetcode.com/problems/k-closest-points-to-origin/) | [Python](https://github.com/qiyuangong/leetcode/blob/master/python/973_K_Closest_Points_to_Origin.py) [Java](https://github.com/qiyuangong/leetcode/blob/master/java/973_K_Closest_Points_to_Origin.java) | 1. Sort and get 0-K, O(nlogn) and O(1)<br>2. Min Heap, O(nlogk) and O(k) |
 | 1064 | [Fixed Point](https://leetcode.com/problems/fixed-point/) &hearts; | [Python](https://github.com/qiyuangong/leetcode/blob/master/python/1064_Fixed_Point.py) [Java](https://github.com/qiyuangong/leetcode/blob/master/java/1064_Fixed_Point.java) | 1. Go through index and value, until find solution encounter index < value, O(n) and O(1)<br>2. Binary search, O(logn) and O(1) |
 
 | # | To Understand |
diff --git a/java/973_K_Closest_Points_to_Origin.java b/java/973_K_Closest_Points_to_Origin.java
@@ -0,0 +1,39 @@
+class Solution {
+/*     public int[][] kClosest(int[][] points, int K) {
+        // Sort
+        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;
+    } */
+
+    private int dist(int[] point) {
+        return point[0] * point[0] + point[1] * point[1];
+    }
+
+    public int[][] kClosest(int[][] points, int K) {
+        // Min Heap with PriorityQueue
+        PriorityQueue<int[]> pq = new PriorityQueue<int[]>((p1, p2) -> dist(p2) - dist(p1));
+        for (int[] p : points) {
+            pq.offer(p);
+            if (pq.size() > K) {
+                pq.poll();
+            }
+        }
+        int[][] res = new int[K][2];
+        while (K > 0) {
+            res[--K] = pq.poll();
+        }
+        return res;
+    }
+}
diff --git a/python/973_K_Closest_Points_to_Origin.py b/python/973_K_Closest_Points_to_Origin.py
@@ -0,0 +1,13 @@
+class Solution(object):
+    # def kClosest(self, points, K):
+    #     """
+    #     :type points: List[List[int]]
+    #     :type K: int
+    #     :rtype: List[List[int]]
+    #     """
+    #     # Sort
+    #     return sorted(points, key=lambda x: x[0] ** 2 + x[1] ** 2)[:K]
+    
+    def kClosest(self, points, K):
+        # K smallest heaq
+        return heapq.nsmallest(K, points, key=lambda x: x[0] ** 2 + x[1] ** 2)
