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lungzeeyim · lungzeeyim · commit 3629f044bb61 · 2017-08-22T23:00:01.000-04:00
diff --git a/5/KSmallest.java b/5/KSmallest.java
@@ -40,14 +40,14 @@ public int[] kSmallestII(int[] array, int k) {
         if (array.length == 0 || k == 0) {
             return new int[0];
         }
-        quickSelect(array, 0, array.length - 1, k - 1);
+        quickSelect(array, 0, array.length - 1, k - 1);               // ( [4,8,5,1], 0, 3, 2 )
         int[] result = Arrays.copyOf(array, k);
         Arrays.sort(result);
         return result;
     }
 
     private void quickSelect(int[] array, int left, int right, int target) {
-        int mid = partition(array, left, right);
+        int mid = partition(array, left, right);                      // mid = 
         if (mid == target) {
             return;
         } else if (target < mid) {
@@ -57,12 +57,12 @@ private void quickSelect(int[] array, int left, int right, int target) {
         }        
     }
 
-    private int partition (int[] array, int left, int right) {
-        int pivot = array[right];
-        int start = left;
-        int end = right - 1;
-        while (start <= end) {
-            if (array[start] < pivot) {
+    private int partition (int[] array, int left, int right) {        // [4,8,5,1], 0, 3
+        int pivot = array[right];                                     // 1
+        int start = left;                                             // 0
+        int end = right - 1;                                          // 2
+        while (start <= end) {                                        // (0, 2)
+            if (array[start] < pivot) {                               //
                 start++;
             } else if (array[end] >= pivot) {
                 end--;
@@ -86,3 +86,17 @@ public static void main(String[] args) {
         System.out.println(Arrays.toString(ks.kSmallestII(data, 3)));
     }
 }
+
+
+
+/*
+a = [4,8,5,1]    k = 3
+
+
+
+
+
+
+
+
+ */
diff --git a/KthSmallestNum.java b/KthSmallestNum.java
@@ -0,0 +1,49 @@
+/*  K-th Smallest Number In Sorted Matrix */
+public class KthSmallestNum {
+    public int kthSmallest(int[][] matrix, int k) {
+        int rows = matrix.length;
+        int columns = matrix[0].length;
+        // Best First Search, 每个值需要一个minheap
+        PriorityQueue<Cell> minHeap = new PriorityQueue<Cell>(k, new Comparator<Cell>() {
+                @Override
+                public int compare(Cell c1, Cell c2) {
+                    if (c1.value == c2.value) {
+                        return 0;
+                    }
+                    return c1.value < c2.value ? -1 : 1;
+                }
+            });
+        // 新生成的对象cell默认开始是true
+        // 避免了多次生成同一个对象
+        boolean[][] visited = new boolean[rows][columns];
+        minHeap.offer(new Cell(0, 0, matrix[0][0]));
+        
+        for (int i = 0; i < k - 1; i++) {
+            Cell cur = minHeap.poll();
+            if (cur.row + 1 < rows && !visited[cur.row + 1][cur.column]) {
+                mminHeap.offer(new Cell(cur.row + 1, cur.column, matrix[cur.row + 1][cur.column]));
+                
+            }
+
+            if (cur.column + 1 < columns && !visited[cur.row][cur.column + 1]) {
+                minHeap.offer(new Cell(cur.row, cur.column + 1, matrix[cur.row][cur.column + 1]));
+
+            }
+
+        }
+        return minHeap.peek().value;
+        
+    }
+
+    static class Cell {
+        int row;
+        int column;
+        int value;
+
+        Cell (int row, int column, int value) {
+            this.row = row;
+            this.column = column;
+            this.value = value;
+        }
+    }
+}
diff --git a/KthSmallestNum.java~ b/KthSmallestNum.java~
@@ -0,0 +1 @@
+public class KthSmallestNum
