Couples Holding Hands

Author: BarthJr

couples-holding-hands.py

@@ -0,0 +1,67 @@
+# There are n couples sitting in 2n seats arranged in a row and want to hold hands.
+#
+# The people and seats are represented by an integer array row where row[i] is the ID of the person sitting in the ith seat.
+# The couples are numbered in order, the first couple being (0, 1), the second couple being (2, 3),
+# and so on with the last couple being (2n - 2, 2n - 1).
+#
+# Return the minimum number of swaps so that every couple is sitting side by side.
+# A swap consists of choosing any two people, then they stand up and switch seats.
+
+"""
+>>> Solution().minSwapsCouples([0,3,5,2,1,4])
+2
+>>> Solution().minSwapsCouples([0,2,1,3])
+1
+>>> Solution().minSwapsCouples([3,2,0,1])
+0
+>>> Solution().minSwapsCouples([1,4,0,5,8,7,6,3,2,9])
+3
+>>> Solution().minSwapsCouples([2,0,5,4,3,1])
+1
+"""
+
+from typing import List
+
+
+class Solution:
+    def minSwapsCouples(self, row: List[int]) -> int:
+        for i in range(len(row)):
+            row[i] = row[i] // 2
+
+        graph = self.createGraph(row)
+        visited = [False for _ in range(len(row) // 2)]
+        swaps = 0
+
+        for i in range(len(row) // 2):
+            if not visited[i]:
+                swaps += self.getClusterSize(graph, visited, i) - 1
+
+        return swaps
+
+    def getClusterSize(self, graph, visited, i):
+        visited[i] = True
+        swaps = 1
+
+        for node in graph[i]:
+            if not visited[node]:
+                swaps += self.getClusterSize(graph, visited, node)
+
+        return swaps
+
+    def createGraph(self, row):
+        graph = {}
+
+        for i in range(len(row) // 2):
+            graph[i] = set()
+
+        for i in range(0, len(row), 2):
+            person1 = row[i]
+            person2 = row[i + 1]
+
+            if person1 == person2:
+                continue
+
+            graph[person1].add(person2)
+            graph[person2].add(person1)
+
+        return graph