3598. 二叉树遍历(华中科技大学考研机试题)

思路：dfs模拟建树

代码：

#include <iostream>
#include <cstring>
#include <algorithm>

using namespace std;

void dfs(string pre, string in){
    
    if(pre.empty()) return ;
    
    char root = pre[0];
    int k = in.find(root);
    dfs(pre.substr(1, k), in.substr(0, k));
    dfs(pre.substr(k + 1), in.substr(k + 1));
    cout << root ;
}
int main()
{
    
    string pre, in;
    while(cin >> pre >> in){
    
        dfs(pre, in);
        cout << endl;
    }
    return 0;
}