✨ Introducing new features.新增一个算法题

Author: crossoverJie

src/main/java/com/crossoverjie/algorithm/BinaryNodeTravel.java

@@ -0,0 +1,121 @@
+package com.crossoverjie.algorithm;
+
+import java.util.LinkedList;
+
+/**
+ * Function: 层序遍历，需要将遍历的节点串联起来
+ *
+ * @author crossoverJie
+ *         Date: 2018/7/27 23:37
+ * @since JDK 1.8
+ */
+public class BinaryNodeTravel {
+
+    private Object data ;
+    private BinaryNodeTravel left ;
+    private BinaryNodeTravel right ;
+    public BinaryNodeTravel next;
+
+    public BinaryNodeTravel() {
+    }
+
+    public BinaryNodeTravel(Object data, BinaryNodeTravel left, BinaryNodeTravel right) {
+        this.data = data;
+        this.left = left;
+        this.right = right;
+    }
+
+    public Object getData() {
+        return data;
+    }
+
+    public void setData(Object data) {
+        this.data = data;
+    }
+
+    public BinaryNodeTravel getLeft() {
+        return left;
+    }
+
+    public void setLeft(BinaryNodeTravel left) {
+        this.left = left;
+    }
+
+    public BinaryNodeTravel getRight() {
+        return right;
+    }
+
+    public void setRight(BinaryNodeTravel right) {
+        this.right = right;
+    }
+
+
+    public BinaryNodeTravel createNode(){
+        BinaryNodeTravel nodeA = new BinaryNodeTravel("A",null,null) ;
+        BinaryNodeTravel nodeB = new BinaryNodeTravel("B",null,null) ;
+        BinaryNodeTravel nodeC = new BinaryNodeTravel("C",null,null) ;
+        BinaryNodeTravel nodeD = new BinaryNodeTravel("D",null,null) ;
+        BinaryNodeTravel nodeE = new BinaryNodeTravel("E",null,null) ;
+        BinaryNodeTravel nodeF = new BinaryNodeTravel("F",null,null) ;
+
+        nodeA.setLeft(nodeB);
+        nodeB.setLeft(nodeD);
+        nodeA.setRight(nodeC);
+        nodeC.setLeft(nodeE);
+        nodeC.setRight(nodeF);
+
+        return nodeA ;
+    }
+
+    @Override
+    public String toString() {
+        return "BinaryNode{" +
+                "data=" + data +
+                ", left=" + left +
+                ", right=" + right +
+                '}';
+    }
+
+
+    /**
+     * 二叉树的层序遍历 借助于队列来实现 借助队列的先进先出的特性
+     *
+     * 首先将根节点入队列 然后遍历队列。
+     *
+     * 暂时把上一个节点存起来，每次都把上一节点的 next 指向当前节点
+     *
+     * 首先将根节点打印出来，接着判断左节点是否为空 不为空则加入队列
+     * @param node
+     */
+    public BinaryNodeTravel levelIterator(BinaryNodeTravel node){
+        LinkedList<BinaryNodeTravel> queue = new LinkedList<>() ;
+
+
+        //暂时存放的上一节点
+        BinaryNodeTravel pre = null;
+
+        //先将根节点入队
+        queue.offer(node) ;
+        BinaryNodeTravel current ;
+        while (!queue.isEmpty()){
+            current = queue.poll();
+
+            //将上一节点指向当前节点
+            if (pre == null){
+                pre = current ;
+            }else {
+                pre.next = current ;
+                pre = current;
+            }
+
+            if (current.getLeft() != null){
+                queue.offer(current.getLeft()) ;
+            }
+            if (current.getRight() != null){
+                queue.offer(current.getRight()) ;
+            }
+        }
+
+        return node ;
+    }
+}

src/test/java/com/crossoverjie/algorithm/BinaryNodeTest.java

@@ -11,7 +11,7 @@ public void test1(){
         node = node.createNode() ;
         System.out.println(node);
 
-        //中序遍历二叉树
+        //层序遍历二叉树
         node.levelIterator(node) ;
 
     }

src/test/java/com/crossoverjie/algorithm/BinaryNodeTravelTest.java

@@ -0,0 +1,21 @@
+package com.crossoverjie.algorithm;
+
+import org.junit.Test;
+
+public class BinaryNodeTravelTest {
+    @Test
+    public void levelIterator() throws Exception {
+        BinaryNodeTravel node = new BinaryNodeTravel() ;
+        //创建二叉树
+        node = node.createNode() ;
+
+        //层序遍历二叉树
+        BinaryNodeTravel binaryNodeTravel = node.levelIterator(node);
+
+        while (binaryNodeTravel != null){
+            System.out.print(binaryNodeTravel.getData() +"--->");
+            binaryNodeTravel = binaryNodeTravel.next;
+        }
+    }
+
+}