题目描述
输入两棵二叉树A，B，判断B是不是A的子结构。（ps：我们约定空树不是任意一个树的子结构）
/**
public class TreeNode {
int val = 0;
TreeNode left = null;
TreeNode right = null;
public TreeNode(int val) {
this.val = val;
}
}
*/
public class Solution {
public boolean HasSubtree(TreeNode root1,TreeNode root2) {
if(root1==null||root2==null){
return false;
}
boolean ret = false;
if(root1.val==root2.val){
ret = isSubTree(root1,root2);
}
if(!ret){
ret = HasSubtree(root1.left,root2);
if(!ret){
ret = HasSubtree(root1.right,root2);
}
}
return ret;
}
public boolean isSubTree(TreeNode root1,TreeNode root2){
if(root2==null){
return true;
}
if(root1==null&&root2!=null){
return false;
}
if(root1.val == root2.val){
boolean left = isSubTree(root1.left,root2.left);
boolean right = isSubTree(root1.right,root2.right);
return left&&right;
}
return false;
}
测试代码
public static void main(String[] args) {
TreeNode root1 = new TreeNode(8);
root1.left = new TreeNode(8);
root1.right = new TreeNode(7);
root1.left.left = new TreeNode(9);
root1.left.right = new TreeNode(2);
TreeNode root2 = new TreeNode(8);
root2.left = new TreeNode(9);
root2.right = new TreeNode(2);
System.out.println(HasSubtree(root1,root2));
}
``
2017.6.1 第二次做
/**
public class TreeNode {
int val = 0;
TreeNode left = null;
TreeNode right = null;
public TreeNode(int val) {
this.val = val;
}
}
*/
public class Solution {
public boolean HasSubtree(TreeNode root1,TreeNode root2) {
if(root1==null || root2==null){
return false;
}
return IsSubtree(root1,root2) ||HasSubtree(root1.left,root2)||HasSubtree(root1.right,root2);
}
public boolean IsSubtree(TreeNode root1, TreeNode root2){
if(root1==null && root2==null){
return true;
}
if(root1==null && root2 !=null){
return false;
}
if(root1!=null && root2 ==null){
return true;
}
if(root1.val!=root2.val){
return false;
}
return IsSubtree(root1.left,root2.left) && IsSubtree(root1.right,root2.right);
}
}
