树的子结构 java

超、凢脫俗 2022-05-06 06:28 147阅读 0赞

## 树的子结构 java ##

**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）

> 代码1：

/**
    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 flag = false;
            if(root1 != null && root2 != null){
                if(root1.val == root2.val){
                    flag = getCompare(root1, root2);
                }
                if(!flag){
                    flag = HasSubtree(root1.left, root2);
                }
                if(!flag){
                    flag = HasSubtree(root1.right, root2);
                }
            }
            return flag;
        }
        
        public boolean getCompare(TreeNode root1,TreeNode root2){
            if(root2 == null){
                return true;
            }
            if(root1 == null){
                return false;
            }
            if(root1.val != root2.val){
                return false;
            }
            return getCompare(root1.left, root2.left) && getCompare(root1.right, root2.right);
        }
    }

> 代码2：

public class Solution {
        public boolean HasSubtree(TreeNode root1,TreeNode root2) {
            boolean flag = false;
            if(root1 != null && root2 != null){
                if(root1.val == root2.val){
                    flag = getCompare(root1, root2);
                }
                if(!flag){
                    flag = HasSubtree(root1.left, root2);
                }
                if(!flag){
                    flag = HasSubtree(root1.right, root2);
                }
            }
            return flag;
        }
        private boolean getCompare(TreeNode root1,TreeNode root2){
            boolean flag = false;
            if(root2 == null){
                flag = true;
            }
            if(root1 != null && root2 != null && root1.val == root2.val){
                flag = getCompare(root1.left, root2.left) && getCompare(root1.right, root2.right);
            }
            return flag;
        }
    }