Create a min heap of elements from first row of 2D array
HeapNode [ ] harr = new HeapNode [ n ] ; for ( int i = 0 ; i < n ; i ++ ) { harr [ i ] = new HeapNode ( mat [ 0 , i ] , 0 , i ) ; } buildHeap ( harr , n ) ; HeapNode hr = new HeapNode ( 0 , 0 , 0 ) ; for ( int i = 1 ; i < k ; i ++ ) {