[백준] 1991 트리 순회

1991번: 트리 순회

#include <iostream>
using namespace std;
struct Node {
    int left;
    int right;
};
Node a[50];
void preorder(int x) {
    if (x == -1) return;
    cout << (char)(x+'A');
    preorder(a[x].left);
    preorder(a[x].right);
}
void inorder(int x) {
    if (x == -1) return;
    inorder(a[x].left);
    cout << (char)(x+'A');
    inorder(a[x].right);
}
void postorder(int x) {
    if (x == -1) return;
    postorder(a[x].left);
    postorder(a[x].right);
    cout << (char)(x+'A');
}
int main() {
    int n;
    cin >> n;
    for (int i=1; i<=n; i++) {
        char x, y, z;
        cin >> x >> y >> z;
        x = x-'A';
        if (y == '.') {
            a[x].left = -1;
        } else {
            a[x].left = y-'A';
        }
        if (z == '.') {
            a[x].right = -1;
        } else {
            a[x].right = z-'A';
        }
    }
    preorder(0);
    cout << '\n';
    inorder(0);
    cout << '\n';
    postorder(0);
    cout << '\n';
    return 0;
}