劍指 Offer - 17:樹的子結構
阿新 • • 發佈:2018-11-26
題目描述
輸入兩棵二叉樹A,B,判斷B是不是A的子結構。(ps:我們約定空樹不是任意一個樹的子結構)
題目連結:https://www.nowcoder.com/practice/6e196c44c7004d15b1610b9afca8bd88
解題思路
遞迴A樹的左右子樹,當遇到根節點同B樹相同的,進行判斷
public class Solution {
public boolean HasSubtree(TreeNode root1, TreeNode root2) {
if (root1 == null || root2 == null) return false;
boolean result = false;
if (root1.val == root2.val) {
result = check(root1, root2);
}
if (!result) {
result = HasSubtree(root1.left, root2);
}
if (!result) {
result = HasSubtree(root1.right, root2) ;
}
return result;
}
private boolean check(TreeNode node1, TreeNode node2) {
if (node2 == null) return true;
if (node1 == null) return false;
if (node1.val != node2.val) return false;
boolean result = true;
result = check(node1.left, node2.left) && check(node1.right, node2.right);
return result;
}
}