leetcode-master/problems/二叉树中递归带着回溯.md

在上一面

class Solution {
private:
    void traversal(TreeNode* cur, string path, vector<string>& result) {
        path += to_string(cur->val); // 中
        if (cur->left == NULL && cur->right == NULL) {
            result.push_back(path);
            return;
        }

        if (cur->left) {
            path += "->";
            traversal(cur->left, path, result); // 左
            path.pop_back(); // 回溯
            path.pop_back(); 
        }
        if (cur->right) {
            path += "->";
            traversal(cur->right, path, result); // 右
            path.pop_back(); // 回溯
            path.pop_back();
        }
    }

public:
    vector<string> binaryTreePaths(TreeNode* root) {
        vector<string> result;
        string path;
        if (root == NULL) return result;
        traversal(root, path, result);
        return result;

    }
};

没有回溯了

class Solution {
private:
    void traversal(TreeNode* cur, string path, vector<string>& result) {
        path += to_string(cur->val); // 中
        if (cur->left == NULL && cur->right == NULL) {
            result.push_back(path);
            return;
        }

        if (cur->left) {
            path += "->";
            traversal(cur->left, path, result); // 左
        }
        if (cur->right) {
            path += "->";
            traversal(cur->right, path, result); // 右
        }
    }

public:
    vector<string> binaryTreePaths(TreeNode* root) {
        vector<string> result;
        string path;
        if (root == NULL) return result;
        traversal(root, path, result);
        return result;

    }
};