copy_list_with_random_pointer

Author: hitzzc

README.md

@@ -121,6 +121,7 @@ Golang solution for leetcode. For each problem, there is a simple *_test.go to t
 #### [135. candy](https://github.com/hitzzc/go-leetcode/tree/master/candy)
 #### [136. single number](https://github.com/hitzzc/go-leetcode/tree/master/single_number)
 #### [137. single number II](https://github.com/hitzzc/go-leetcode/tree/master/single_number_II)
+#### [138. copy_list_with_random_pointer](https://github.com/hitzzc/go-leetcode/tree/master/copy_list_with_random_pointer)
 
 
 

copy_list_with_random_pointer/copy_list_with_random_pointer.cpp

@@ -0,0 +1,44 @@
+#include <unordered_map>
+using namespace std;
+
+struct RandomListNode {
+	int label;
+	RandomListNode *next, *random;
+	RandomListNode(int x) : label(x), next(NULL), random(NULL) {}
+};
+
+class Solution {
+public:
+	RandomListNode *copyRandomList(RandomListNode *head) {
+		if (head==NULL) return NULL;
+		auto fake = new RandomListNode(0);
+		unordered_map<RandomListNode*, RandomListNode*> mapping;
+		auto ptr = head;
+		auto pre_copy = fake;
+		while (ptr!=NULL){
+			RandomListNode* copy_node;
+			if (mapping.find(ptr)!=mapping.end())
+				copy_node = mapping[ptr];
+			else{
+				copy_node = new RandomListNode(ptr->label);
+				mapping[ptr] = copy_node;
+			}
+			pre_copy->next = copy_node;
+			pre_copy = pre_copy->next;
+
+			if (ptr->random!=NULL){
+				RandomListNode* copy_node_random;
+				if (mapping.find(ptr->random)!=mapping.end()){
+					copy_node_random = mapping[ptr->random];
+				}
+				else{
+					copy_node_random = new RandomListNode(ptr->random->label);
+					mapping[ptr->random] = copy_node_random;
+				}
+				copy_node->random = copy_node_random;
+			}
+			ptr = ptr->next;
+		}
+		return fake->next;
+	}
+};