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  1. #include<iostream>
  2. #include<queue>
  3. #include<vector>
  4. using namespace std;
  5.  
  6. typedef pair<int, pair<int,int> > node;
  7. vector<int> mergeKSortedArray(vector<vector<int> > arr){
  8.     vector<int>result;
  9.     priority_queue<node, vector<node>, greater<node> > pq;//min priority queue
  10.     //insert 0th element of each arr to pq
  11.     for(int i=0;i<arr.size();i++){
  12.         pq.push({arr[i][0],{i,0}});//we need to store 3 things - val of ele, index of arr, index of ele
  13.     }
  14.     //remove the ele one by one from min heap and add it to the result vector
  15.     while(!pq.empty()){
  16.         node current = pq.top();
  17.         pq.pop();
  18.         int element = current.first;
  19.         int x = current.second.first;//row in which element is present
  20.         int y = current.second.second;//col in which element is present
  21.  
  22.         result.push_back(element);
  23.         //you need to push in pq the next element of current x,y+1
  24.         if(y+1<arr.size()){
  25.             pq.push({arr[x][y+1],{x,y+1}});
  26.         }
  27.     }
  28.     return result;
  29. }
  30. int main(){
  31.     vector<vector<int> >arr{{2,6,12,15},
  32.                             {1,3,14,20},
  33.                             {3,5,8,10}};
  34.  
  35.     vector<int>output = mergeKSortedArray(arr);
  36.     for(auto x:output){
  37.         cout<<x<<" ";
  38.     }
  39.  
  40.  
  41.  
  42. return 0;}
  43.  
Success #stdin #stdout 0s 4228KB
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https://ideone.com/PPKsHE
language:
C++ (gcc 8.3)
created:
5 years ago
visibility:
secret

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