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) {
boolean result = false;
if(root1 == null || root2 == null) return false;
else{
if(root1.val == root2.val) result = doequal(root1,root2);
//判断上一个if是否得出true
if(!result) result = HasSubtree(root1.left,root2);//遍历树,在1中找到与2的跟相等的元素。
if(!result) result = HasSubtree(root1.right,root2);
}
return result;
}
public boolean doequal(TreeNode root1,TreeNode root2) {
//拟子目录先遍历完,即为真
if(root2 == null) return true;
//拟父目录先走完,即为假
if(root1 == null) return false;
//对比过程中元素不相等,为假
if(root1.val != root2.val) return false;
//把拟子目录与父目录上元素对比
return (doequal(root1.right,root2.right)&&doequal(root1.left,root2.left));
}
}