7-11 玩转二叉树 (25分)

#include<iostream>
#include<cstdio>
#include<vector>
#include<algorithm>
#include<cstring>
#include<string>
#include<map>
#include<set>
#include<queue>
#include<iomanip>
#include<stack>
using namespace std;
#define STDIN freopen("in.in", "r", stdin);freopen("out.out", "w", stdout);


const int N = 100;

int pre[N], mid[N];
int n;
int le[N], ri[N];
int build(int l1, int r1, int l2, int r2)
{
    if (l1 > r1 || l2 > r2) return 0;
    int rt = pre[l2];
    int j = l1;
    for (int i = l1; i <= r1; i++)
    {
        if (rt == mid[i]) {
            j = i;
            break;
        }
    }
    int cnt = j - l1;

    le[rt] = build(l1, j-1, l2 + 1, l2 + cnt);
    ri[rt] = build(j + 1, r1, l2 + cnt + 1, r2);
    return rt;

}
int main()
{
    //STDIN
    cin >> n;
    for (int i = 1; i <= n; i++) cin >> mid[i];
    for (int i = 1; i <= n; i++) cin >> pre[i];
    le[0] = build(1, n, 1, n);
    queue<int> que;
    que.push(le[0]);
    vector<int> ans;
    while(que.size())
    {
        auto t = que.front();
        que.pop();
        ans.push_back(t);
        if (ri[t] > 0) que.push(ri[t]);
        if (le[t] > 0) que.push(le[t]);
    }
    int len = ans.size();
    for (int i = 0 ; i < len; i++) printf("%d%c", ans[i], " \n"[i == len-1]);
}