Day 18 K Closest Points

Author: Bogdan Hladiuc

Formation/21_Days_Challenge/Day_18_K_Closest_Points/KClosestPoints.cs

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+
+#nullable disable warnings
+namespace Formation {
+
+    public class KClosestPoints {
+        public static void Run() {
+            var points = new Point[] {
+                new Point {
+                    X = 2,
+                    Y = 0
+                },
+                new Point {
+                    X = 0,
+                    Y = 2
+                },
+                new Point {
+                    X = 3,
+                    Y = 3
+                },
+                new Point {
+                    X = 4,
+                    Y = 2
+                },
+                new Point {
+                    X = 2,
+                    Y = 5
+                }
+            };
+            var K = 3;
+
+            var result = Solution(points, K);
+            
+            if (result == null) {
+                return;
+            }
+            
+            foreach (var point in result) {
+                Console.WriteLine($"({point.X}, {point.Y})");
+            }
+        }
+        
+        private static Point[] Solution(Point[] points, int K) {
+            if (points.Length < K) {
+                return null;
+            }
+            
+            var pq = new PriorityQueue<Point, double>(Comparer<double>.Create((x, y) => y.CompareTo(x)));
+            
+            foreach (var point in points) {
+                pq.Enqueue(point, point.Dist);
+                
+                while (pq.Count > K) {
+                    pq.Dequeue();
+                }
+            }
+
+            return pq.UnorderedItems.Select(item => item.Element).ToArray();
+        }
+
+        private class Point {
+            public int X { get; set; }
+            public int Y { get; set; }
+
+            public double Dist {
+                get {
+                    return Math.Sqrt(this.X * this.X + this.Y * this.Y);
+                }
+            }
+        }
+    }
+}