Merge pull request pranjay-poddar#184 from JayantGoel001/master

Create MergeKSortedList.cpp

Author: pranjay-poddar

CONTRIBUTERS.md

@@ -68,3 +68,4 @@
 * @Chayan-11
 * @riya1916
 * @Samriddh2703
+* @JayantGoel001

Leetcode Solutions/c++/MergeKSortedList.cpp

@@ -0,0 +1,59 @@
+/*
+You are given an array of k linked-lists lists, each linked-list is sorted in ascending order.
+Merge all the linked-lists into one sorted linked-list and return it.
+*/
+
+
+#include <bits/stdc++.h>
+#define pil pair<int,ListNode *>
+using namespace std;
+// Defining a struct of ListNode
+struct ListNode {
+    int val;
+    ListNode *next;
+    ListNode() : val(0), next(nullptr) {}
+    ListNode(int x) : val(x), next(nullptr) {}
+    ListNode(int x, ListNode *next) : val(x), next(next) {}
+};
+ListNode* mergeKLists(vector<ListNode*>& lists) {
+    //creating a priority queue with elements in increasing order.
+    priority_queue<pil,vector<pil>,greater<pil>> pq;
+
+    //Inserting a pair of integer and ListNode head.
+    for(auto it : lists){
+        if(it){
+            pq.push({it->val,it});
+        }
+    }
+    //Creating A New head pointer to store merged Lists.
+    ListNode *temp = new ListNode();
+    ListNode *head = temp;
+
+    //Iterating till priority queue gets empty.
+    while(!pq.empty()){
+
+        // Popping the smallest element.
+        pil top = pq.top();
+        pq.pop();
+
+        // Pointing head pointer to smallest element pointer.
+        temp->next = top.second;
+
+        //Checking if next element exists on current list or not.
+        if(top.second->next){
+            pq.push({top.second->next->val,top.second->next});
+        }
+        temp = temp->next;
+    }
+    return head->next;
+}
+/*
+Input : 
+[
+  1->4->5,
+  1->3->4,
+  2->6
+]
+Output : 
+1->1->2->3->4->4->5->6
+*/