closestpairofpoints.py

Author: souravmondaldev

Divide and Conquer/closestpairofpoints.py

@@ -0,0 +1,25 @@
+from math import sqrt, pow
+
+def distance(a, b):
+  return sqrt(pow(a[0] - b[0],2) + pow(a[1] - b[1],2))
+
+def bruteMin(points, current=float("inf")):
+  if len(points) < 2: return current
+  else:
+    head = points[0]
+    del points[0]
+    newMin = min([distance(head, x) for x in points])
+    newCurrent = min([newMin, current])
+    return bruteMin(points, newCurrent)
+
+def divideMin(points):
+  points = sorted(points)
+  half = len(sorted(points))/2
+  minimum = min([bruteMin(points[:half]), bruteMin(points[half:])])
+  nearLine = filter(lambda x: x[0] > half - minimum and x[0] < half + minimum, points)
+  return min([bruteMin(nearLine), minimum])
+
+list1 = [(12,30), (40, 50), (5, 1), (12, 10), (3,4)]
+list2=[(1, 496.5), (12,30), (40, 50), (5, 1), (12, 10), (3,4), (1, 496), (1, 497)]
+print "Closest Pair Distance:",divideMin(list1)
+print "Closest Pair Distance:",divideMin(list2)