这个题要注意的是：右节点时大于等于根节点的。

#include
     
      #include
      
       using namespace std;const int maxn = 1e3 + 10;int pre[maxn], n;bool is;vector
       
        ss;void f(int l, int r){    if (l > r)return;    int tr = l + 1;    int tl = r;    if (!is){        while (tr <= r&&pre[tr] < pre[l])tr++;        while (tl > l&&pre[tl]>=pre[l])--tl;    }    else{        while (tr <= r&&pre[tr] >= pre[l])tr++;        while (tl > l&&pre[tl] < pre[l])--tl;    }    if (tr - tl != 1)return;    f(l + 1, tl);        f(tr, r);    ss.push_back(pre[l]);}int main(){    cin >> n;    for (int i = 0; i < n; ++i)cin >> pre[i];    f(0, n - 1);    if (ss.size() != n){        is = 1;        ss.clear();        f(0, n - 1);    }    if (ss.size() != n)cout << "NO" << endl;    else{        cout << "YES" << endl;        cout << ss[0];        for (int i = 1; i < n; ++i)            cout << " " << ss[i];        cout << endl;    }}