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）
思路
Two Recursion:
- Find in Tree 1 if there is a tree node in Tree 1 equal to the root of Tree 2
- In this case, compare the every node in Tree 2 with Tree1, and then return the result.
代码
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/**
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) {
boolean result = false;
if(root1 != null && root2 != null){
if(root1.val == root2.val){
result = ifRoot1HasRoot2(root1,root2);
}
//find in left node
if(!result){
result = HasSubtree(root1.left,root2);
}
//find in right node
if(!result){
result = HasSubtree(root1.right,root2);
}
}
return result;
}
public boolean ifRoot1HasRoot2(TreeNode root1,TreeNode root2){
boolean result = false;
if(root2 == null){
result = true;
}
if(root1 != null && root2!= null){
if(root1.val == root2.val){
result = ifRoot1HasRoot2(root1.left,root2.left)
&&ifRoot1HasRoot2(root1.right,root2.right);
}else{
result = false;
}
}
return result;
}
}
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