小编给大家分享一下Java算法中二叉树的练习题有哪些，相信大部分人都还不怎么了解，因此分享这篇文章给大家参考一下，希望大家阅读完这篇文章后大有收获，下面让我们一起去了解一下吧！
解法
/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode() {}
* TreeNode(int val) { this.val = val; }
* TreeNode(int val, TreeNode left, TreeNode right) {
* this.val = val;
* this.left = left;
* this.right = right;
* }
* }
*/
class Solution {
int i = 0;
int res = 0;
public int kthSmallest(TreeNode root, int k) {
method(root,k);
return res;
}
public void method(TreeNode root, int k){
if(root==null) return ;
method(root.left,k);
i++;
if(i==k){
res = root.val;
return ;
}
method(root.right,k);
}
}
解法
/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode() {}
* TreeNode(int val) { this.val = val; }
* TreeNode(int val, TreeNode left, TreeNode right) {
* this.val = val;
* this.left = left;
* this.right = right;
* }
* }
*/
class Solution {
int sum = 0;
public TreeNode convertBST(TreeNode root) {
method(root);
return root;
}
public void method(TreeNode root) {
if(root==null){
return;
}
method(root.right);
sum+=root.val;
root.val = sum;
method(root.left);
}
}
解法
/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode() {}
* TreeNode(int val) { this.val = val; }
* TreeNode(int val, TreeNode left, TreeNode right) {
* this.val = val;
* this.left = left;
* this.right = right;
* }
* }
*/
class Solution {
public boolean isValidBST(TreeNode root) {
return method(root,null,null);
}
public boolean method(TreeNode root,TreeNode min,TreeNode max){
if(root==null) return true;
if(min!=null&&root.val<=min.val) return false;
if(max!=null&&root.val>=max.val) return false;
return method(root.left,min,root)&&method(root.right,root,max);
}
}
解法
/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode() {}
* TreeNode(int val) { this.val = val; }
* TreeNode(int val, TreeNode left, TreeNode right) {
* this.val = val;
* this.left = left;
* this.right = right;
* }
* }
*/
class Solution {
public TreeNode searchBST(TreeNode root, int val) {
if(root==null) return null;
if(root.val==val) return root;
if(root.val>=val){
return searchBST(root.left,val);
}
if(root.val<val){
return searchBST(root.right,val);
}
return null;
}
}
解法
/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode() {}
* TreeNode(int val) { this.val = val; }
* TreeNode(int val, TreeNode left, TreeNode right) {
* this.val = val;
* this.left = left;
* this.right = right;
* }
* }
*/
class Solution {
public TreeNode insertIntoBST(TreeNode root, int val) {
return method(root,val);
}
public TreeNode method(TreeNode root, int val){
if(root==null) return new TreeNode(val);
if (root.val < val)
root.right = insertIntoBST(root.right, val);
if (root.val > val)
root.left = insertIntoBST(root.left, val);
return root;
}
}
算法
/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode() {}
* TreeNode(int val) { this.val = val; }
* TreeNode(int val, TreeNode left, TreeNode right) {
* this.val = val;
* this.left = left;
* this.right = right;
* }
* }
*/
class Solution {
public TreeNode deleteNode(TreeNode root, int key) {
if (root == null) return null;
if (root.val == key){
if (root.left == null) return root.right;
if (root.right == null) return root.left;
TreeNode minNode = getMin(root.right);
root.right = deleteNode(root.right, minNode.val);
minNode.left = root.left;
minNode.right = root.right;
root = minNode;
}else if(root.val>key){
root.left = deleteNode(root.left,key);
}else{
root.right = deleteNode(root.right,key);
}
return root;
}
TreeNode getMin(TreeNode node) {
while (node.left != null) node = node.left;
return node;
}
}以上是“Java算法中二叉树的练习题有哪些”这篇文章的所有内容，感谢各位的阅读！相信大家都有了一定的了解，希望分享的内容对大家有所帮助，如果还想学习更多知识，欢迎关注亿速云行业资讯频道！
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