树model
package com.sly.uploadfile.algorithm;
/**
* Created by fmgao on 2019/7/24.
*/
public class TreeNode01<T> {
T value;
TreeNode01<T> leftChild;
TreeNode01<T> rightChild;
TreeNode01() {
}
TreeNode01(T value) {
this.value = value;
}
/**
* 增加左子节点
*
* @param value
*/
public void addLeft(T value) {
TreeNode01<T> leftChild = new TreeNode01<T>();
this.leftChild = leftChild;
}
/**
* 增加右子节点
*
* @param value
*/
public void addRight(T value) {
TreeNode01<T> rightChild = new TreeNode01<>();
this.rightChild = rightChild;
}
@Override
public boolean equals(Object obj) {
if (!(obj instanceof TreeNode01)) {
return false;
}
return this.value.equals(((TreeNode01<?>) obj).value);
}
@Override
public int hashCode() {
return this.value.hashCode();
}
@Override
public String toString() {
return this.value == null ? "" : this.value.toString();
}
}
树的基本操作
package com.sly.uploadfile.algorithm;
import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;
import java.util.Queue;
/**
* Created by fmgao on 2019/7/24.
*/
public class TreeNodeTools {
/**
* 判断树种节点个数
*
* @param root
* @param <T>
* @return
*/
public static <T> int getTreeNum(TreeNode01<T> root) {
if (root == null) {
return 0;
}
return getTreeNum(root.leftChild) + getTreeNum(root.rightChild) + 1;
}
/**
* 判断树的深度
*
* @param root
* @param <T>
* @return
*/
public static <T> int getTreeDepth(TreeNode01<T> root) {
if (root == null) {
return 0;
}
int leftDepth = getTreeDepth(root.leftChild) + 1;
int rightDepth = getTreeDepth(root.rightChild) + 1;
return Math.max(leftDepth, rightDepth);
}
/**
* 前序遍历
*
* @param root
* @param <T>
*/
public static <T> void preOrderTravel(TreeNode01<T> root) {
if (root == null) {
return;
}
visitNode(root);
preOrderTravel(root.leftChild);
preOrderTravel(root.rightChild);
}
/**
* 中序遍历
*
* @param root
* @param <T>
*/
public static <T> void midOrderTravel(TreeNode01<T> root) {
if (root == null) {
return;
}
midOrderTravel(root.leftChild);
visitNode(root);
midOrderTravel(root.rightChild);
}
/**
* 后续遍历
*
* @param root
* @param <T>
*/
public static <T> void backOrderTravel(TreeNode01<T> root) {
if (root == null) {
return;
}
backOrderTravel(root.leftChild);
backOrderTravel(root.rightChild);
visitNode(root);
}
/**
* 访问node节点
*
* @param node01
* @param <T>
*/
public static <T> void visitNode(TreeNode01<T> node01) {
System.out.println(node01.value + "\t");
}
/**
* 分层遍历
*
* @param root
* @param <T>
*/
public static <T> void levelTravel(TreeNode01<T> root) {
Queue<TreeNode01<T>> q = new LinkedList<TreeNode01<T>>();
q.offer(root);
while (!q.isEmpty()) {
TreeNode01<T> tmp = q.poll();
visitNode(tmp);
if (tmp.leftChild != null) {
q.offer(tmp.leftChild);
}
if (tmp.rightChild != null) {
q.offer(tmp.rightChild);
}
}
}
/**
* 求第K层节点个数
*
* @param root
* @param k
* @param <T>
* @return
*/
public static <T> int getNumForKLevel(TreeNode01<T> root, int k) {
if (root == null || k < 1) {
return 0;
}
if (k == 1) {
return 1;
}
int leftNum = getNumForKLevel(root.leftChild, k - 1);
int rightNum = getNumForKLevel(root.rightChild, k - 1);
return leftNum + rightNum;
}
/**
* 求二叉树种叶子节点的个数
*
* @param root
* @param <T>
* @return
*/
public static <T> int getLeafNum(TreeNode01<T> root) {
if (root == null) {
return 0;
}
if (root.leftChild == null && root.rightChild == null) {
return 1;
}
int leftNum = getLeafNum(root.leftChild);
int rightNum = getLeafNum(root.rightChild);
return leftNum + rightNum;
}
/**
* 交换根节点的左右子树
*
* @param root
* @param <T>
* @return
*/
public static <T> TreeNode01<T> exchange(TreeNode01<T> root) {
if (root == null) {
return null;
}
TreeNode01<T> left = exchange(root.leftChild);
TreeNode01<T> right = exchange(root.rightChild);
root.leftChild = right;
root.rightChild = left;
return root;
}
/**
* 查看node是否是root的节点
*
* @param root
* @param node
* @param <T>
* @return
*/
public static <T> boolean nodeIsChild(TreeNode01<T> root, TreeNode01<T> node) {
if (root == null || node == null) {
return false;
}
if (root == node) {
return true;
}
boolean isFind = nodeIsChild(root.leftChild, node);
if (!isFind) {
isFind = nodeIsChild(root.rightChild, node);
}
return isFind;
}
/**
* 返回lNode 和 rNode 以root为根节点的公共父节点
*
* @param root
* @param lNode
* @param rNode
* @param <T>
* @return
*/
public static <T> TreeNode01<T> findAllFatherNode(TreeNode01<T> root, TreeNode01<T> lNode, TreeNode01<T> rNode) {
if (lNode == root || rNode == root) {
return root;
}
if (root == null || lNode == null || rNode == null) {
return null;
}
// 如果lNode是左子树的节点
if (nodeIsChild(root.leftChild, lNode)) {
if (nodeIsChild(root.rightChild, rNode)) {
return root;
} else {
return findAllFatherNode(root.leftChild, lNode, rNode);
}
} else {
if (nodeIsChild(root.leftChild, rNode)) {
return root;
} else {
return findAllFatherNode(root.rightChild, lNode, rNode);
}
}
}
/**
* 根据前序和中序构建二叉树
*
* @param pre
* @param mid
* @param <T>
* @return
*/
public static <T> TreeNode01<T> getTreeFromPreAndMid(List<T> pre, List<T> mid) {
if (pre == null || mid == null || pre.size() == 0 || mid.size() == 0) {
return null;
}
if (pre.size() == 1) {
return new TreeNode01<T>(pre.get(0));
}
TreeNode01<T> root = new TreeNode01<T>(pre.get(0));
// 找出根节点在中序中的位置
int index = 0;
while (!mid.get(index++).equals(pre.get(0))) {
}
// 构建左子树的前序
List<T> preLeft = new ArrayList<T>(index);
// 中子树的前序
List<T> midLeft = new ArrayList<T>(index);
for (int i = 1; i < index; i++) {
preLeft.add(pre.get(i));
}
for (int i = 0; i < index - 1; i++) {
midLeft.add(mid.get(i));
}
// 重建左子树
root.leftChild = getTreeFromPreAndMid(preLeft, midLeft);
// 右子树的前序
List<T> preRight = new ArrayList<T>(pre.size() - index - 1);
// 右子树的中序
List<T> midRight = new ArrayList<T>(pre.size() - index - 1);
for (int i = 0; i <= pre.size() - index - 1; i++) {
preRight.add(pre.get(index + i));
}
for (int i = 0; i <= pre.size() - index - 1; i++) {
midRight.add(mid.get(index + i));
}
// 重建→子树
root.rightChild = getTreeFromPreAndMid(preRight, midRight);
return root;
}
public static <T> boolean equals(TreeNode01<T> node1, TreeNode01<T> node2) {
if (node1 == null && node2 == null) {
return true;
} else if (node1 == null || node2 == null) {
return false;
}
boolean isEqual = node1.value.equals(node2.value);
boolean isLeftEqual = equals(node1.leftChild, node2.leftChild);
boolean isRightEqual = equals(node1.rightChild, node2.rightChild);
return isEqual && isLeftEqual && isRightEqual;
}
}
