uva 536

给出二叉树先序和中序遍历打印出后序遍历结果。
这一题跟之前的 uva 548有一些类似，可以对照着学习
代码如下，特备注意dfs的时候递归条件心里要清楚，否则出错很麻烦：

#include <iostream>#include <cstdio>#include <cstdlib>#include <cstring>#include <map>#include <set>using namespace std;const int maxn = 1000 + 10;string pre_order,in_order;int lch[maxn],rch[maxn];int build(int l1,int r1,int l2,int r2){    if(l1>r1) return 0;    int root = pre_order[l1]-'A'+1;    int p = l2;    while(in_order[p]-'A'+1 != root) p++;    int cnt = p-l2;    lch[root] = build(l1+1,l1+cnt,l2,p-1);    rch[root] = build(l1+cnt+1,r1,p+1,r2);    return root;}void solve(int root){    if(lch[root]) solve(lch[root]);    if(rch[root]) solve(rch[root]);    char ch = 'A'+root-1;    cout<<ch;}int  main(){    while(cin >> pre_order ){        memset(lch,0,sizeof(lch));        memset(rch,0,sizeof(rch));        cin >> in_order;        int len = pre_order.length();        build(0,len-1,0,len-1);        solve(pre_order[0]-'A'+1);        cout<<endl;        /*for(int i = 0;i<10;i++){            cout<<i<<":"<<lch[i]<<","<<rch[i]<<endl;        }*/    }    return 0;}