Leetcode 23 Merge k Sorted Lists Solution in c++ | Hindi Coding Community

 

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. 

Example 1:

Input: lists = [[1,4,5],[1,3,4],[2,6]]

Output: [1,1,2,3,4,4,5,6]

Explanation: The linked-lists are:

[

  1->4->5,

  1->3->4,

  2->6

]

merging them into one sorted list:

1->1->2->3->4->4->5->6

Example 2:

Input: lists = []

Output: []

Example 3:

Input: lists = [[]]

Output: []

class Solution {

public:

ListNode* mergeKLists(vector<ListNode*>& lists) {

int count =0;

for(auto it : lists){

if(it == NULL)count++;

}

if(count == lists.size())return NULL;

vector<int> v;

for(auto it : lists){

while(it!=NULL){

v.push_back(it->val);

it = it->next;

}

}

sort(v.begin(), v.end());

ListNode* a = new ListNode(v[0]);

ListNode * b = a;

for(int i = 0; i<v.size()-1; i++){

b->next = new ListNode(v[i+1]);

b = b->next;

}

return a;

}

};