[LeetCode]606. Construct String from Binary Tree

[LeetCode]606. Construct String from Binary Tree

题目描述

思路

二叉树的先序遍历扩展，注意处理子节点为空的三种情况

代码

#include <iostream>
#include <string>

using namespace std;

struct TreeNode {
    int val;
    TreeNode* left;
    TreeNode* right;
    TreeNode(int x) :val(x), left(NULL), right(NULL) {}
};

class Solution {
public:
    string tree2str(TreeNode* t) {
        if (t == NULL) return "";
        if (t->left == NULL && t->right == NULL) return to_string(t->val) + "";
        if (t->right == NULL) return to_string(t->val) + "(" + tree2str(t->left) + ")";
        return to_string(t->val) + "(" + tree2str(t->left) + ")" + "(" + tree2str(t->right) + ")";
    }
};

int main() {
    TreeNode* t1 = new TreeNode(1);
    TreeNode* t2 = new TreeNode(2);
    TreeNode* t3 = new TreeNode(3);
    TreeNode* t4 = new TreeNode(4);

    t1->left = t2;
    t1->right = t3;
    t2->left = t4;

    Solution s;

    cout << s.tree2str(t1) << endl;
    system("pause");
}