Kth smallest number in Sorted Matrix

Find the kth smallest number in at row and column sorted matrix.

Example

Given k = and 4 a matrix:

[  [1 ,5 ,7],  [3 ,7 ,8],  [4 ,8 ,9],]

Return5.

Analysis:

Although the matrix is horizontally and vertically sorted, there are no rule to find the next smallest number. In this solution, we'll put the numbers in the first row to a heap, and remove the smallest one and add a new number who Se position is right under the removed one.

Note:when requesting to find the kth largest/smallest number, you should consider heap sort.

1  Public classSolution {2     /**3 * @param matrix:a matrix of integers4 * @param k:an integer5 * @return: the kth smallest number in the matrix6      */7      Public intKthsmallest (int[] Matrix,intk) {8         if(Matrix = =NULL|| Matrix.length = =0|| matrix[0].length = =0) {9             return 0;Ten         } One         if(k > Matrix.length * matrix[0].length) { A             return 0; -         } -         returnVertical (matrix, k); the     } -      -     Private intVerticalint[] Matrix,intk) { -queue<point> heap =NewPriorityqueue<point> (k,NewComparator<point>() { +              Public intCompare (Point-left, point-right) { -                 returnLeft.val-Right.val; +             } A         }); at          for(inti =0; I < Math.min (matrix[0].length, K); i++) { -Heap.offer (NewPoint (0, I, matrix[0][i])); -         } -          for(inti =1; I <= K-1; i++) { -Point Curr =Heap.poll (); -             if(Curr.row +1<matrix.length) { inHeap.offer (NewPoint (Curr.row +1, Curr.col, Matrix[curr.row +1][curr.col])); -             } to         } +         returnHeap.peek (). val; -     } the } *  $ classPoint {Panax Notoginseng          Public intRow, col, Val; -          PublicPoint (intRowintColintval) { the              This. Row =Row; +              This. Col =Col; A              This. val =Val; the         } +}

Kth smallest number in Sorted Matrix