给出前序和中序遍历，输出后序遍历

#include <iostream>#include <string>#include <algorithm>#include <vector>using namespace std;int n,pos;vector<int> pre,in,post;void rec(int l,int r){    if(l>=r)        return;    int root = pre[pos++];    int m = distance(in.begin(),find(in.begin(),in.end(),root));    rec(l,m);    rec(m+1,r);    post.push_back(root);}void solve(){    pos = 0;    rec(0,pre.size());    for(int i=0;i<n;i++){        if(i)            cout<<" ";        cout<<post[i];    }    cout<<endl;}int main(){    int k;    cin>>n;    for(int i=0;i<n;i++){        cin>>k;        pre.push_back(k);    }    for(int i=0;i<n;i++){        cin>>k;        in.push_back(k);    }    solve();}