Create number-of-connected-components-in-an-undirected-graph.ot

Author: kamyu104

Python/number-of-connected-components-in-an-undirected-graph.ot

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+# Time:  O(nlog*n) ~= O(n), n is the length of the positions
+# Space: O(n)
+
+class UnionFind(object):
+    def __init__(self, n):
+        self.set = range(n)
+        self.count = n
+
+    def find_set(self, x):
+       if self.set[x] != x:
+           self.set[x] = self.find_set(self.set[x])  # path compression.
+       return self.set[x]
+
+    def union_set(self, x, y):
+        x_root, y_root = map(self.find_set, (x, y))
+        if x_root != y_root:
+            self.set[min(x_root, y_root)] = max(x_root, y_root)
+            self.count -= 1
+
+
+class Solution(object):
+    def countComponents(self, n, edges):
+        """
+        :type n: int
+        :type edges: List[List[int]]
+        :rtype: int
+        """
+        union_find = UnionFind(n)
+        for i, j in edges:
+            union_find.union_set(i, j)
+        return union_find.count