Create code.cpp

Heap/Merge k Sorted Linkedlist/code.cpp

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+// C++ program to merge k sorted arrays of size n each
+#include <bits/stdc++.h>
+using namespace std;
+
+// Linked List node
+struct Node {
+	int data;
+	Node* next;
+};
+
+/* Function to print nodes in
+a given linked list */
+void printList(Node* node)
+{
+	while (node != NULL) {
+		printf("%d ", node->data);
+		node = node->next;
+	}
+}
+
+// The main function that
+// takes an array of lists
+// arr[0..last] and generates
+// the sorted output
+Node* mergeKLists(Node* arr[], int last)
+{
+
+	// Traverse form second list to last
+	for (int i = 1; i <= last; i++) {
+		while (true) {
+			// head of both the lists,
+			// 0 and ith list.
+			Node *head_0 = arr[0], *head_i = arr[i];
+
+			// Break if list ended
+			if (head_i == NULL)
+				break;
+
+			// Smaller than first element
+			if (head_0->data >= head_i->data) {
+				arr[i] = head_i->next;
+				head_i->next = head_0;
+				arr[0] = head_i;
+			}
+			else
+				// Traverse the first list
+				while (head_0->next != NULL) {
+					// Smaller than next element
+					if (head_0->next->data
+						>= head_i->data) {
+						arr[i] = head_i->next;
+						head_i->next = head_0->next;
+						head_0->next = head_i;
+						break;
+					}
+					// go to next node
+					head_0 = head_0->next;
+
+					// if last node
+					if (head_0->next == NULL) {
+						arr[i] = head_i->next;
+						head_i->next = NULL;
+						head_0->next = head_i;
+						head_0->next->next = NULL;
+						break;
+					}
+				}
+		}
+	}
+
+	return arr[0];
+}
+
+// Utility function to create a new node.
+Node* newNode(int data)
+{
+	struct Node* temp = new Node;
+	temp->data = data;
+	temp->next = NULL;
+	return temp;
+}
+int main()
+{
+	// Number of linked lists
+	int k = 3;
+
+	// Number of elements in each list
+	int n = 4;
+
+	// an array of pointers storing the
+	// head nodes of the linked lists
+	Node* arr[k];
+
+	arr[0] = newNode(1);
+	arr[0]->next = newNode(3);
+	arr[0]->next->next = newNode(5);
+	arr[0]->next->next->next = newNode(7);
+
+	arr[1] = newNode(2);
+	arr[1]->next = newNode(4);
+	arr[1]->next->next = newNode(6);
+	arr[1]->next->next->next = newNode(8);
+
+	arr[2] = newNode(0);
+	arr[2]->next = newNode(9);
+	arr[2]->next->next = newNode(10);
+	arr[2]->next->next->next = newNode(11);
+
+	// Merge all lists
+	Node* head = mergeKLists(arr, k - 1);
+
+	printList(head);
+
+	return 0;
+}