day 14: 138-copy-list-with-random-pointer

138-copy-list-with-random-pointer/driver.cpp

@@ -0,0 +1,30 @@
+#include "soln.hpp"
+
+int main()
+{
+	Node n1(7);
+	Node n2(13);
+	Node n3(11);
+	Node n4(10);
+	Node n5(1);
+	n1.next = &n2;
+	n2.next = &n3;
+	n2.random = &n1;
+	n3.next = &n4;
+	n3.random = &n5;
+	n4.next = &n5;
+	n4.random = &n3;
+	n5.random = &n1;
+
+	Solution soln;
+	Node *n_1 = soln.copyRandomList(&n1);
+
+	Node *h1 = &n1, *h_1 = n_1;
+	while (h1 != nullptr && h_1 != nullptr)
+	{
+		cout << h1->val << ", " << ((h1->random != nullptr) ? h1->random->val : -9999) << endl;
+		cout << h_1->val << ", " << ((h_1->random != nullptr) ? h_1->random->val : -9999) << endl;
+		h1 = h1->next, h_1 = h_1->next;
+	}
+	return 0;
+}

138-copy-list-with-random-pointer/soln.cpp

@@ -0,0 +1,71 @@
+#include "soln.hpp"
+
+void Solution::insertNode(Node *head, Node *newnode)
+{
+	newnode->next = head->next;
+	head->next = newnode;
+}
+Node *Solution::copyRandomList(Node *head)
+{
+	if (head == nullptr)
+	{
+		return nullptr;
+	}
+	vector<pair<int, Node *>> nodemap;
+	vector<pair<int, int>> randindexmap;
+	Node *current = head;
+	for (int i = 0; current != nullptr; i++)
+	{
+		nodemap.push_back(pair<int, Node *>{i, current});
+		current = current->next;
+	}
+
+	for (auto it : nodemap)
+	{
+		if (it.second->random == nullptr)
+		{
+			randindexmap.push_back(pair<int, int>{it.first, -1});
+			continue;
+		}
+		for (auto itr : nodemap)
+		{
+			if (it.second->random == itr.second)
+			{
+				randindexmap.push_back(pair<int, int>{it.first, itr.first});
+				break;
+			}
+		}
+	}
+
+	Node *new_head_ptr = new Node(nodemap[0].second->val);
+	current = new_head_ptr;
+	for (int i = 1; i < nodemap.size(); i++)
+	{
+		Node *new_node = new Node(nodemap[i].second->val);
+		insertNode(current, new_node);
+		current = current->next;
+	}
+
+	nodemap.clear();
+	current = new_head_ptr;
+	for (int i = 0; current != nullptr; i++)
+	{
+		nodemap.push_back(pair<int, Node *>{i, current});
+		current = current->next;
+	}
+
+	for (int i = 0; i < nodemap.size(); i++)
+	{
+
+		if (randindexmap[i].second == -1)
+		{
+			nodemap[i].second->random = nullptr;
+		}
+		else
+		{
+			nodemap[i].second->random = nodemap[randindexmap[i].second].second;
+		}
+	}
+
+	return new_head_ptr;
+}

138-copy-list-with-random-pointer/soln.hpp

@@ -0,0 +1,24 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+class Node
+{
+public:
+	int val;
+	Node *next;
+	Node *random;
+
+	Node(int _val)
+	{
+		val = _val;
+		next = NULL;
+		random = NULL;
+	}
+};
+
+class Solution
+{
+public:
+	void insertNode(Node *head, Node *newnode);
+	Node *copyRandomList(Node *head);
+};