base structure

data_structure/link_list/RangList.java

@@ -0,0 +1,105 @@
+package link_list;
+/** 
+ *@author liujun
+ *@date： 2018-8-22 下午02:06:33
+ *@author—Email:ljfirst@mail.ustc.edu.cn
+ *@description:
+ *1. 判断单聊表是否有环
+ *2. 找出带环单链表的入口
+ *@version 1.0
+ */
+public class RangList extends SinglyLinkedList{
+
+	public RangList(int value) {
+		super(value);
+		// TODO Auto-generated constructor stub
+	}
+
+	@Override
+	//尾插法改写为构造有环链表
+	public SinglyLinkedList insertTail(int[] list) {
+		System.out.println("尾插法改写为构造有环链表");
+		SinglyLinkedList point = null;
+		SinglyLinkedList first = point;
+		//环入口结点
+		SinglyLinkedList temp = new SinglyLinkedList();
+		//尾插法，循环赋值
+		for (int i = 0; i < list.length; i++) {
+			SinglyLinkedList link = new SinglyLinkedList(list[i]);
+			//首次判断
+			if (first == null) {
+				first = point = link;
+			}
+			//环入口结点
+			if(i == list.length/2){
+				temp = link;
+				System.out.println("插入点："+temp.value);
+			}
+			point.next = link;
+			point = point.next;
+		}
+		//为节点构造环
+		point.next = temp;
+		return first;
+	}
+
+	//判断单链表是否有环
+	public boolean FindListTail(SinglyLinkedList first) {
+		// TODO Auto-generated method stub
+		SinglyLinkedList slow = first;
+		SinglyLinkedList fast = first;
+
+		while (fast.next != null && fast != null) {
+			fast = fast.next.next;
+			slow = slow.next;
+			if (fast == slow) {
+				return true;
+			}
+		}
+		return false;
+	}
+
+	//返回单链表环的相遇点
+	public SinglyLinkedList ListMeet(SinglyLinkedList first) {
+
+		SinglyLinkedList slow = first;
+		SinglyLinkedList fast = first;
+
+		while (fast != null && fast.next != null) {
+			fast = fast.next.next;
+			slow = slow.next;
+			if (fast == slow) {
+				return fast;
+			}
+		}
+		return null;
+	}
+
+	//找出带环单链表的入口
+	public SinglyLinkedList findLoopPort(SinglyLinkedList first) {
+		// TODO Auto-generated method stub
+
+		SinglyLinkedList point_meet = ListMeet(first);
+		while(first != null && point_meet != null){
+			if(first == point_meet){
+				return point_meet;
+			}
+			first = first.next;
+			point_meet = point_meet.next;
+		}
+		return null;
+	}
+
+	//主方法测试
+	public static void main(String[] args) {
+
+		//构造有环单链表
+		int[] array = {1,2,3,4,5,6,7,8,9,10};
+		RangList rl = new RangList(0);
+		SinglyLinkedList first= rl.insertTail(array);
+
+		//测试单链表是否有环
+		System.out.println(rl.FindListTail(first));
+		System.out.println(rl.ListMeet(first).value);
+	}
+}

data_structure/link_list/SinglyLinkedList.java

@@ -21,6 +21,11 @@ public class SinglyLinkedList {
 	int value;
 	SinglyLinkedList next = null;
 
+	public SinglyLinkedList() {
+		// TODO Auto-generated constructor stub
+		this.value = 0;
+	}
+
 	public SinglyLinkedList(int value) {
 		// TODO Auto-generated constructor stub
 		this.value = value;
@@ -130,6 +135,7 @@ public void printLink(SinglyLinkedList first) {
 	//主方法测试
 	public static void main(String[] args) {
 //		Map  s = new HashMap<Integer, Integer>(12);
+		//first是表头结点(含值0，后续被替换)
 		SinglyLinkedList first = new SinglyLinkedList(0);
 		int[] array = {1,2,3,4,5,6,7,8,9,10};
 		first = first.insertTail(array);

data_structure/tree/Tree.java

@@ -0,0 +1,102 @@
+package tree;
+
+import java.util.LinkedList;
+import java.util.Queue;
+
+/** 
+ *@author liujun
+ *@date： 2018-7-21 下午01:13:08
+ *@author—Email:ljfirst@mail.ustc.edu.cn
+ *@description:树、二叉树、先序遍历赋值二叉树、
+ *中序遍历赋值二叉树，后序遍历赋值二叉树
+ *其中二叉树包含：二叉树的数据结构、二叉树的三种遍历赋值、二叉树的层次遍历、二叉树的按行打印	
+ *@version 1.0
+ */
+public class Tree {
+
+	public static void main(String[] args) {
+		binary_tree root = new binary_tree();
+		int [] tree_num ={1,5,7,-1,-1,-1,8,6,3,-1,-1,2,-1,-1,9,-1,-1};
+
+		//先序构建二叉树
+		root = root.create_preOrder(root, tree_num, 0);
+		//二叉树层次遍历
+		root.levelTraverse(root);
+	}
+}
+
+//二叉树的数据结构
+class binary_tree{
+
+	binary_tree left;   //左孩子
+	binary_tree right;  //右孩子
+	int value = 0;      //默认二叉树的值为0
+	public static int count = 0;//定义一个全局静态计数变量
+
+	public binary_tree(int value) {
+		// TODO Auto-generated constructor stub
+		this.value = value;
+	}
+
+	public binary_tree() {
+		// TODO Auto-generated constructor stub
+	}
+
+	//二叉树的三种遍历赋值
+	//将数组先序遍历赋值二叉树,约定-1是空指针
+	public binary_tree create_preOrder(binary_tree root, int [] tree_num ,int i){
+
+		if(i < tree_num.length){
+			if(tree_num[i] == -1){
+				root = null;
+			}else{
+				//new root's lchild and rchild
+				binary_tree lchild = new binary_tree();
+				binary_tree rchild = new binary_tree();
+				//preOrder
+				root.value = tree_num[i];
+				//不用++count，构造的时候或出错
+				root.left = create_preOrder(lchild, tree_num, ++count);
+				root.right = create_preOrder(rchild, tree_num, ++count);
+			}
+		}
+
+		return root;
+	}
+
+	//将数组中序遍历赋值二叉树
+	public binary_tree create_inOrder(binary_tree root){
+
+		return root;
+	}
+
+	//将数组后序遍历赋值二叉树
+	public binary_tree create_postOrder(binary_tree root){
+
+	    return root;
+    }
+
+	//清零操作
+	public void clear(){
+		count = 0;
+	}
+	//二叉树的层次遍历,使用栈来辅助实现
+	public void levelTraverse(binary_tree root){
+
+		// Queue is just an interface, LinkedList is Realization
+		Queue<binary_tree> queue = new LinkedList<binary_tree>();
+		queue.offer(root);
+		while(!queue.isEmpty()){
+			binary_tree note = queue.poll();
+			System.out.print(note.value + " ");
+			if(note.left != null){
+				levelTraverse(note.left);
+			}
+			if(note.right != null){
+				levelTraverse(note.right);
+			}
+		}
+	}
+
+	// 二叉树的按行打印
+}