11月2号

今天上完数据结构课后留了三道力扣上的题目，我在今天完成了前两道题目。

今天上完课后去科技楼开会，开完会走的时候还碰上了王建民老师，还说我们晚上有点闲，要给我们找活干，我们可一点也不闲啊......

 

94题：二叉树的中序遍历

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
 *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
 * };
 */
class Solution {
public:
void dotree(TreeNode* root,vector<int>*vec){
    if(root){
        if(root->left){
            dotree(root->left,vec);
        }
        vec->push_back(root->val);
        if(root->right){
            dotree(root->right,vec);
        }
    }
}
    vector<int> inorderTraversal(TreeNode* root) {
        vector<int>vec;
        dotree(root,&vec);
        return vec;
    }
};

194题：二叉树的最近公共祖先

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
    TreeNode* lowestCommonAncestor(TreeNode* root, TreeNode* p, TreeNode* q) {
        if(!root||root==p||root==q) return root;
        TreeNode* left=lowestCommonAncestor(root->left,p,q);
        TreeNode* right=lowestCommonAncestor(root->right,p,q);
        if(!left) return right;
        if(!right) return left;
        return root;
    }
};