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树的子结构
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)
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 flag = false;
if (root1 != null && root2 != null){
if (root1.val == root2.val){
flag = doesTree1haveTree2(root1, root2);
}
if(flag == false){
flag = HasSubtree(root1.left, root2);
}
if(flag == false){
flag = HasSubtree(root1.right, root2);
}
}
return flag;
}
public boolean doesTree1haveTree2(TreeNode root1, TreeNode root2){
if(root2 == null){
return true;
}
if(root1 == null || root1.val != root2.val){
return false;
}
return doesTree1haveTree2(root1.left,root2.left) && doesTree1haveTree2(root1.right,root2.right);
}
}