no message

Author: Chris Wu

problems/clone-graph.py

@@ -54,8 +54,28 @@ def cloneGraph(self, start):
 
         return clone[start]
 
-
-
+#2020/8/7, similar to 2
+class Solution(object):
+    def cloneGraph(self, node):
+        if not node: return node
+        
+        visited = set()
+        clones = {}
+        stack = []
+        
+        stack.append(node)
+        while stack:
+            curr = stack.pop()
+            if curr in visited: continue
+            visited.add(curr)
+            clones[curr] = Node(curr.val)
+            stack.extend(curr.neighbors)
+        
+        for curr in clones:
+            clones[curr].neighbors = [clones[c] for c in curr.neighbors]
+        
+        return clones[node]
+        
 
 
 

problems/copy-list-with-random-pointer.py

@@ -31,4 +31,29 @@ def copyRandomList(self, head):
             curr = curr.next
             curr_copy = curr_copy.next
 
-        return head_copy
+        return head_copy
+
+# 2020/8/11
+class Solution(object):
+    def copyRandomList(self, head):
+        if not head: return head
+        
+        clones = {}
+        
+        curr = head
+        while curr:
+            clones[curr] = Node(curr.val)
+            curr = curr.next
+        
+        curr = head
+        while curr:
+            if curr.next: clones[curr].next = clones[curr.next]
+            if curr.random: clones[curr].random = clones[curr.random]
+            curr = curr.next
+        
+        return clones[head]
+
+"""
+Time: O(N). Two iteration. First iteration make a the clones. Second iteration setup the links.
+Space: O(1). No extra space except the cloned node.
+"""