堆的replace 和 heapify 的实现

Xikl · Jan 5, 2019 · bc97b20 · bc97b20
1 parent 3a91e37
commit bc97b20
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diff --git a/src/main/java/com/ximo/datastructuresinaction/array/Array.java b/src/main/java/com/ximo/datastructuresinaction/array/Array.java
@@ -1,5 +1,7 @@
 package com.ximo.datastructuresinaction.array;
 
+import java.util.Arrays;
+
 /**
  * 自己的一个数组类
  *
@@ -23,6 +25,12 @@ public Array(int capacity) {
         size = 0;
     }
 
+    @SuppressWarnings("unchecked")
+    public Array(E[] arr) {
+        data = (E[])Arrays.stream(arr).toArray();
+        size = arr.length;
+    }
+
     public Array() {
         this(10);
     }

diff --git a/src/main/java/com/ximo/datastructuresinaction/heap/MaxHeap.java b/src/main/java/com/ximo/datastructuresinaction/heap/MaxHeap.java
@@ -29,6 +29,21 @@ public MaxHeap() {
         data = new Array<>();
     }
 
+    /**
+     * 找到最后一个叶子节点，然后找到他的父亲节点
+     *
+     *
+     *
+     * @param arr
+     */
+    public MaxHeap(E[] arr) {
+        data = new Array<>(arr);
+        // 找到最后一个叶子节点，然后找到他的父亲节点
+        for (int cur = getParentIndex(arr.length - 1); cur >= 0; cur--) {
+            siftDown(cur);
+        }
+    }
+
     public int size() {
         return data.getSize();
     }
@@ -111,5 +126,21 @@ public int getMaxOnLeftAndRightValueIndex(int index) {
         return leftLessThanRight ? rightChildIndex : leftChildIndex;
     }
 
+    /**
+     * 取出堆中最大的元素，并替换为新的元素
+     * 再进行下沉操作
+     *
+     * @param newValue 一个新的值
+     * @return 堆中的最大值
+     */
+    public E replace(E newValue) {
+        E max = findMax();
+        data.set(0, newValue);
+        siftDown(0);
+        return max;
+    }
+
+
+
 
 }
diff --git a/src/test/java/com/ximo/datastructuresinaction/array/ArrayTest.java b/src/test/java/com/ximo/datastructuresinaction/array/ArrayTest.java
@@ -1,6 +1,5 @@
 package com.ximo.datastructuresinaction.array;
 
-import com.ximo.datastructuresinaction.array.Array;
 import org.junit.Test;
 
 /**
@@ -25,4 +24,10 @@ public void testToString() {
 //        System.out.println(arr.toString());
     }
 
+    @Test
+    public void testArrToMyArray() {
+        Integer[] arr = {1, 2, 3};
+        Array<Integer> array = new Array<>(arr);
+        System.out.println(array);
+    }
 }