refactor 378

Author: fishercoder1534

src/main/java/com/fishercoder/solutions/_378.java

@@ -23,7 +23,28 @@ public int kthSmallest(int[][] matrix, int k) {
         }
     }
 
+
     public static class Solution2 {
+        /**
+         * use heap data structure
+         */
+        public int kthSmallest(int[][] matrix, int k) {
+            PriorityQueue<int[]> heap = new PriorityQueue<>((a, b) -> Integer.compare(a[0], b[0]));
+            for (int i = 0; i < Math.min(matrix.length, k); i++) {
+                //we store value, rowIndex, colIndex as an array into this heap
+                heap.offer(new int[]{matrix[i][0], i, 0});
+            }
+            while (k-- > 1) {
+                int[] min = heap.poll();
+                if (min[2] + 1 < matrix[min[1]].length) {
+                    heap.offer(new int[]{matrix[min[1]][min[2] + 1], min[1], min[2] + 1});
+                }
+            }
+            return heap.poll()[0];
+        }
+    }
+
+    public static class Solution3 {
         /**
          * Binary Search : The idea is to pick a mid number, then compare it with the elements in each row, we start form
          * end of row util we find the element is less than the mid, the left side element is all less than mid; keep tracking elements
@@ -53,24 +74,4 @@ public int kthSmallest(int[][] matrix, int k) {
             return lo;
         }
     }
-
-    public static class Solution3 {
-        /**
-         * use heap data structure
-         */
-        public int kthSmallest(int[][] matrix, int k) {
-            PriorityQueue<int[]> heap = new PriorityQueue<>((a, b) -> a[0] - b[0]);
-            for (int i = 0; i < matrix.length; i++) {
-                //we store value, rowIndex, colIndex as an array into this heap
-                heap.offer(new int[]{matrix[i][0], i, 0});
-            }
-            while (k-- > 1) {
-                int[] min = heap.poll();
-                if (min[2] + 1 < matrix[min[1]].length) {
-                    heap.offer(new int[]{matrix[min[1]][min[2] + 1], min[1], min[2] + 1});
-                }
-            }
-            return heap.poll()[0];
-        }
-    }
 }