PAT天梯赛题目集：Level2-006.树的遍历

题 ： https://www.patest.cn/contests/gplt/L2-006

 

#include <iostream>
#include <vector>
using std::cin;
using std::cout;
std::vector<int> PostOrder_Traversal, InOrder_Traversal;
std::vector<int> &post = PostOrder_Traversal, &in = InOrder_Traversal;
std::vector<int> LevelOrder_Traversal(10000, -1), &level = LevelOrder_Traversal;
void solve(int start, int end, int root, int index) {
    if (start > end)
        return;
    int i = start;
    while (i < end && in[i] != post[root])
        i++;
    level.at(index) = post.at(root);
    solve(start, i - 1, root - (end - i) - 1, 2 * index + 1);
    solve(i + 1, end, root - 1, 2 * index + 2);
}
int main() {
    std::ios::sync_with_stdio(false);
    cin.tie(false);

    int TreeNode_Num;
    int &N = TreeNode_Num;
    int cnt = 0;
    cin >> N;
    post.resize(N);
    in.resize(N);
    for (int i = 0; i < N; ++i)
        cin >> post[i];
    for (int i = 0; i < N; ++i)
        cin >> in[i];
    solve(0, N - 1, N - 1, 0);
    for (int i = 0; i < level.size(); ++i) {
        if (level.at(i) != -1 && cnt++ != N - 1) 
            cout << level.at(i) << ' ';
        else if (level.at(i) != -1) {
            cout << level.at(i);
            break;
        }
    }
    return 0;
}