代码如下

#include<iostream>
#include<algorithm>
#include<sstream>
#include<string>
using namespace std;
const int N=10000+5;
int in_order[N],post_order[N],lch[N],rch[N];
int n;
bool read_list(int* a) {
	string line;
	if(!getline(cin,line)) return false;
	stringstream ss(line);
	n=0;
	int x;
	while (ss>>x) a[n++]=x;
	return n>0;
}
int build(int L1,int R1,int L2,int R2) {
	if(L1>R1) return 0;
	int root=post_order[R2];
	int p=L1;
	while(in_order[p]!=root) p++; 
	int cnt=p-L1;
	in_order[root]=build(L1,p-1,L2,L2+cnt-1);
	post_order[root]=build(p+1,R1,L2+cnt,R2-1);
	return root;
}
int best,best_sum;
void dfs(int u,int sum) {
	sum+=u;
	if(!lch[u]&&!rch[u]){
		if(sum<best||(sum==best&&u<best_sum)){
			best=sum;
			best_sum=u;
		}
	}
	if(lch[u]) dfs(lch[u],sum);
	if(rch[u]) dfs(lch[u],sum);
}
int main() {
	while(read_list(in_order)) {
		read_list(post_order);
		build(0,n-1,0,n-1);
		best_sum=1e6;
		dfs(post_order[n-1],0);
		cout<<best<<"\n";
	}
	return 0;
}