题解 | #二叉树遍历#

#include <iostream>
#include <vector>
#include<map>

using namespace std;

struct tree {
    struct tree* l=nullptr;
    struct tree* r=nullptr;
    char val='\0';
};
string input;
int index=0;
void build(tree*& root) {
    if (input[index] == '#') {
        index++;
        return;
    }
    else {
        root=new tree();
        root->val = input[index];
        index++;
        build(root->l);
        build(root->r);
    }
}
void mid(tree* r) {
    if (r == nullptr) {
        return;
    }
    mid(r->l);
    cout << r->val << ' ';
    mid(r->r);
}
int main() {
    tree* root;
    cin >> input;
    build(root);
    mid(root);
    return 0;
}