leetcode/606-20231208-pass/main.cpp

#include<stdcpp.h>
using namespace std;
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) {}
};
void create(int * val, int cnt, TreeNode *cur,int idx){
    int left_idx = (idx + 1) * 2 - 1;
    int right_idx = (idx + 1) * 2 ;
    if(left_idx >= cnt && right_idx >= cnt) {
        cur->left = nullptr;
        cur->right = nullptr;
        return;
    }
    if(val[left_idx] == -1 || left_idx >= cnt){
        cur -> left = nullptr;
    }else{
        TreeNode * left_child = new TreeNode(val[left_idx]);
        cur->left = left_child;
        create(val,cnt,left_child,left_idx);
    }
    if(val[right_idx] == -1 || right_idx >= cnt){
        cur -> right = nullptr;
    }else{
        TreeNode * right_child = new TreeNode(val[right_idx]);
        cur->right = right_child;
        create(val, cnt, right_child, right_idx);
    }
    return;
}
void traverse(TreeNode* node){
    cout<<node->val<<' ';
    if(node->left != nullptr){
        traverse(node->left);
    }
    if(node->right != nullptr){
        traverse(node->right);
    }
    return;
}
TreeNode* createTree(int * val, int cnt){
    TreeNode * root = new TreeNode(val[0]);
    cout<<"create a tree"<<endl;
    create(val,cnt,root, 0);
    traverse(root);
    cout<<"\ndone"<<endl;
    return root;
}

class Solution{
    public:
    string traverse(TreeNode * node, string &str){
        str.push_back((char)('0'+node->val));
        if(node -> left == nullptr && node -> right == nullptr) return str;
        if(node -> left == nullptr){
            str.push_back('(');
            str.push_back(')');
        }else{
            str.push_back('(');
            traverse(node->left, str);
            str.push_back(')');
        }
        if(node -> right == nullptr){
            return str;
        }else{
            str.push_back('(');
            traverse(node->right, str);
            str.push_back(')');
            return str;
        }
        
    }
    string tree2str(TreeNode * root){
        string rlt = "";
        return traverse(root,rlt);
    }

};

int main(){
    Solution sol;
    int ex1_val[4] = {1,2,3,4};
    TreeNode * ex1 = createTree(ex1_val,4);
    cout<<sol.tree2str(ex1)<<endl;
    int ex2_val[5] = {1,2,3,-1,4};
    TreeNode * ex2 = createTree(ex2_val, 5);
    cout<<sol.tree2str(ex2)<<endl;

    return 0;
}