Merge K sorted linked lists

Author: spaceman-dev

Heaps/MergeKSortedLinkedLists.cpp

@@ -0,0 +1,116 @@
+// { Driver Code Starts
+// C++ program to merge k sorted arrays of size n each
+#include <bits/stdc++.h>
+using namespace std;
+
+// A Linked List node
+struct Node
+{
+int data;
+Node* next;
+
+Node(int x){
+ data = x;
+ next = NULL;
+}
+
+};
+
+/* Function to print nodes in a given linked list */
+void printList(Node* node)
+{
+while (node != NULL)
+{
+printf("%d ", node->data);
+node = node->next;
+}
+cout<<endl;
+}
+
+ // } Driver Code Ends
+/*Linked list Node structure
+
+struct Node
+{
+int data;
+Node* next;
+
+Node(int x){
+ data = x;
+ next = NULL;
+}
+
+};
+*/ 
+
+class Solution{
+ public:
+ Node* merge(Node* node1, Node* node2)
+ {
+ if(!node1)
+ return node2;
+ if(!node2)
+ return node1;
+ if(node1->data < node2->data)
+ {
+ node1->next = merge(node1->next, node2);
+ return node1;
+ }
+ else
+ {
+ node2->next = merge(node1, node2->next);
+ return node2;
+ }
+ }
+ //Function to merge K sorted linked list.
+ Node * mergeKLists(Node *arr[], int K)
+ {
+ // Your code here
+ Node* node = NULL;
+ for(int i = 0 ; i < K ; i++)
+ node = merge(node, arr[i]);
+ return node;
+ }
+};
+
+
+
+// { Driver Code Starts.
+// Driver program to test above functions
+int main()
+{
+ int t;
+ cin>>t;
+ while(t--)
+ {
+ int N;
+ cin>>N;
+ struct Node *arr[N];
+ for(int j=0;j<N;j++)
+ {
+ int n;
+ cin>>n;
+
+ int x;
+ cin>>x;
+ arr[j]=new Node(x);
+ Node *curr = arr[j];
+ n--;
+
+ for(int i=0;i<n;i++)
+ {
+ cin>>x;
+ Node *temp = new Node(x);
+ curr->next =temp;
+ curr=temp;
+ }
+	}
+	Solution obj;
+	Node *res = obj.mergeKLists(arr,N);
+printList(res);
+
+ }
+
+return 0;
+}
+ // } Driver Code Ends

Heaps/README.md

@@ -58,3 +58,17 @@
  extractMin() since the heap is empty thus
   no min element exist so -1
   is printed.
+
+## 5. Merge K Sorted Linked Lists:
+ Given K sorted linked lists of different sizes. The task is to merge them in such a way that after merging they will be a single sorted linked list.
+ Example 1:
+ Input:
+ K = 4
+ value = {{1,2,3},{4 5},{5 6},{7,8}}
+ Output: 1 2 3 4 5 5 6 7 8
+ Explanation: The test case has 4 sorted linked list of size 3, 2, 2, 2
+  1st list 1 -> 2-> 3
+  2nd list 4->5
+  3rd list 5->6
+  4th list 7->8
+  The merged list will be 1->2->3->4->5->5->6->7->8.