my c++ solution


  • 0
    J
    /**
     * 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* str2tree(string s) {
            if(s.size()==0) return NULL;
            int pos = s.find_first_of('(');
            if(pos==std::string::npos)
            {
                TreeNode*root = new TreeNode(stoll(s));
                return root;
            }
            int val = stoll(s.substr(0,pos));
            stack<char>stk;
            stk.push(s[pos]);
            pos++;//skip '('
            int left = pos;
            while(!stk.empty()&&pos++ < s.size())
            {
                if(pos<s.size() && (s[pos]=='('||s[pos]==')'))
                {
                    if(s[pos]=='(')stk.push('(');
                    if(s[pos]==')')stk.pop();
                }
            }
            TreeNode *root = new TreeNode(val);
            string leftpart = s.substr(left,pos-left);
            root->left = str2tree(leftpart);
            if(pos+2<s.size())
            {
                string rightpart = s.substr(pos+2);
                if(rightpart.size()>0) rightpart.pop_back();
                root->right = str2tree(rightpart);
            }
            return root;
        }
    };
    

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