[4661] Falling Leaves

https://www.acmicpc.net/problem/4661

4661번: Falling Leaves

사실 동국대학교 자료구조 시간에 과제로 풀었던 문제인데 2000 mid icpc 문제라 백준에도 있더라구요 ㅋㅋ

#include <iostream>
#include <string>
using namespace std;
 
string preorder(int level, string leaves[]);
 
int main(void) {
    string input_line;
    do {
        string* leaves = new string[26];
        int level = 0;
        getline(std::cin, input_line);
        while (input_line[0] != '$' && input_line[0] != '*') {
            leaves[level] = input_line;
            level++;
            getline(std::cin, input_line);
        }
        cout << preorder(level, leaves) << "\n";
    } while (input_line[0] == '*');
}
 
string preorder(int level, string leaves[]) {
    while (level > 0 && leaves[level - 1].length() == 0) {
        level--;
    }
    if (level == 0) {
        return "";
    }
    level--;
    char root = leaves[level][0];
    string* left = new string[level];
    string* right = new string[level];
    for (int i = 0; i < level; i++) {
        int past = 0;
        while ((past < int(leaves[i].length())) && (leaves[i][past] < root)) {
            past++;
        }
        left[i] = leaves[i].substr(0, past);
        right[i] = leaves[i].substr(past);
    }
    return (root + preorder(level, left) + preorder(level, right));
}