update heap

src/main/java/git/snippet/heap/Code_DistanceLessK.java → src/main/java/git/snippet/heap/DistanceLessK.java

@@ -7,7 +7,7 @@ import java.util.PriorityQueue;
 // 几乎有序是指，如果把数组排好顺序的话，每个元素移动的距离一定不超过k，并且k相对于数组长度来说是比较小的。
 // 请选择一个合适的排序策略，对这个数组进行排序。(从小到大)
 // tips: 加k个数进堆，然后再加入一个，弹出一个，最后堆里面剩下的继续弹出即可 时间复杂度：O(N*logK)
-public class Code_DistanceLessK {
+public class DistanceLessK {
     public static void sortedArrDistanceLessK(int[] arr, int k) {
         k = Math.min(arr.length - 1, k);
         PriorityQueue<Integer> heap = new PriorityQueue<>();
@@ -20,7 +20,9 @@ public class Code_DistanceLessK {
         for (; i < arr.length; i++) {
             heap.offer(arr[i]);
             // 移动一定不会超过K次
-            arr[index++] = heap.poll();
+            if (!heap.isEmpty()) {
+                arr[index++] = heap.poll();
+            }
         }
         while (!heap.isEmpty()) {
             arr[index++] = heap.poll();

src/test/java/git/snippet/common/Generator.java

 package git.snippet.common;
 
+import java.util.Arrays;
+
 public class Generator {
+    // for test
+    // 几乎有序的数组排序测试
+    public static int[] randomArrayNoMoveMoreK(int maxSize, int maxValue, int K) {
+        int[] arr = new int[(int) ((maxSize + 1) * Math.random())];
+        for (int i = 0; i < arr.length; i++) {
+            arr[i] = (int) ((maxValue + 1) * Math.random()) - (int) (maxValue * Math.random());
+        }
+        // 先排个序
+        Arrays.sort(arr);
+        // 然后开始随意交换，但是保证每个数距离不超过K
+        // swap[i] == true, 表示i位置已经参与过交换
+        // swap[i] == false, 表示i位置没有参与过交换
+        boolean[] isSwap = new boolean[arr.length];
+        for (int i = 0; i < arr.length; i++) {
+            int j = Math.min(i + (int) (Math.random() * (K + 1)), arr.length - 1);
+            if (!isSwap[i] && !isSwap[j]) {
+                isSwap[i] = true;
+                isSwap[j] = true;
+                int tmp = arr[i];
+                arr[i] = arr[j];
+                arr[j] = tmp;
+            }
+        }
+        return arr;
+    }
+
     // for test
     public static int[] generateRandomArray(int maxSize, int maxValue) {
         // Math.random() -> [0,1)

src/test/java/git/snippet/heap/Code_DistanceLessKTest.java → src/test/java/git/snippet/heap/DistanceLessKTest.java

@@ -7,10 +7,8 @@ import org.junit.jupiter.api.Test;
 
 import java.util.Arrays;
 
-import static org.junit.jupiter.api.Assertions.*;
-
 @DisplayName("几乎有序的数组排序测试")
-public class Code_DistanceLessKTest {
+public class DistanceLessKTest {
 
     @Test
     @DisplayName("几乎有序的数组排序测试")
@@ -20,39 +18,12 @@ public class Code_DistanceLessKTest {
         int maxValue = 100;
         for (int i = 0; i < testTime; i++) {
             int k = (int) (Math.random() * maxSize) + 1;
-            int[] arr = randomArrayNoMoveMoreK(maxSize, maxValue, k);
+            int[] arr = Generator.randomArrayNoMoveMoreK(maxSize, maxValue, k);
             int[] arr1 = Generator.copyArray(arr);
             int[] arr2 = Generator.copyArray(arr);
-            Code_DistanceLessK.sortedArrDistanceLessK(arr1, k);
+            DistanceLessK.sortedArrDistanceLessK(arr1, k);
             Arrays.sort(arr2);
             Assertions.assertArrayEquals(arr1, arr2);
         }
     }
-
-
-    // for test
-    public static int[] randomArrayNoMoveMoreK(int maxSize, int maxValue, int K) {
-        int[] arr = new int[(int) ((maxSize + 1) * Math.random())];
-        for (int i = 0; i < arr.length; i++) {
-            arr[i] = (int) ((maxValue + 1) * Math.random()) - (int) (maxValue * Math.random());
-        }
-        // 先排个序
-        Arrays.sort(arr);
-        // 然后开始随意交换，但是保证每个数距离不超过K
-        // swap[i] == true, 表示i位置已经参与过交换
-        // swap[i] == false, 表示i位置没有参与过交换
-        boolean[] isSwap = new boolean[arr.length];
-        for (int i = 0; i < arr.length; i++) {
-            int j = Math.min(i + (int) (Math.random() * (K + 1)), arr.length - 1);
-            if (!isSwap[i] && !isSwap[j]) {
-                isSwap[i] = true;
-                isSwap[j] = true;
-                int tmp = arr[i];
-                arr[i] = arr[j];
-                arr[j] = tmp;
-            }
-        }
-        return arr;
-    }
-
 }
\ No newline at end of file