🌕🌗 剑指 Offer 26. 树的子结构

难度: 🌕🌗

问题描述

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解法

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
class Solution {
    public boolean isSubStructure(TreeNode A, TreeNode B) {
        // 思路：
        // 
        if(B == null) {
            return false;
        }
        return mySol1(A, B);
    }

    private boolean mySol1(TreeNode root, TreeNode b) {
        // 递归终止条件
        if(root == null) {
            return false;
        }
        // System.out.println(root.val);
        if(mySol(root, b)) {
            return true;
        }
        return mySol1(root.left, b) || mySol1(root.right, b);
    }

    private boolean mySol(TreeNode a, TreeNode b) {
        // 递归终止条件
        if(b == null) {
            return true;
        }
        if(a == null) {
            return false;
        }
        if(a.val != b.val) {
            return false;
        }
        return mySol(a.left, b.left) && mySol(a.right, b.right);
    }
}

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输出