delete pics to save space

2.548.cpp

@@ -0,0 +1,56 @@
+#include<iostream>
+#include<string>
+#include<sstream>
+#include<algorithm>
+using namespace std;
+const int maxv=10000+10;
+int in_order[maxv],post_order[maxv],lch[maxv],rch[maxv];
+int n;
+bool read_list(int *a)
+{
+	string line;
+	if(!getline(cin,line)) return 0;
+	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;
+	lch[root]=build(L1,p-1,L2,L2+cnt-1);
+	rch[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||(sum==best_sum&&u<best))
+		{
+			best=u;
+			best_sum=sum;
+		}
+	}
+	if(lch[u]) dfs(lch[u],sum);
+	if(rch[u]) dfs(rch[u],sum);
+}
+int main()
+{
+	while(read_list(in_order))
+	{
+		read_list(post_order);
+		build(0,n-1,0,n-1);
+		best_sum=1000000000;
+		dfs(post_order[n-1],0);
+		cout<<best<<endl;
+	}
+	return 0;
+}