Binary Tree Paths Problem


Description

LeetCode Problem 257.

Given the root of a binary tree, return all root-to-leaf paths in any order.

A leaf is a node with no children.

Example 1:

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Input: root = [1,2,3,null,5]
Output: ["1->2->5","1->3"]

Example 2:

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Input: root = [1]
Output: ["1"]

Constraints:

  • The number of nodes in the tree is in the range [1, 100].
  • -100 <= Node.val <= 100


Sample C++ Code

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class Solution {
public:
    void dfs(TreeNode* root, vector<string> &result, string s) {
        if (root->left == NULL && root->right == NULL) {
            result.push_back(s);
            return;
        }
        if (root->left)
            dfs(root->left, result, s + "->" + to_string(root->left->val));
        if (root->right)
            dfs(root->right, result, s + "->" + to_string(root->right->val));
        return;
    }
    vector<string> binaryTreePaths(TreeNode* root) {
        vector<string> result;
        if (root == NULL)
            return result;
        dfs(root, result, to_string(root->val));
        return result;
    }
};




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