uva 548 Tree

//提交通过，0.092，不算太快，先给出代码

 

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define MAX 10010
#define INF 100000010
struct treenode
{
    int data,lchild,rchild,level;
};
int *start,*flag;
int min,leaf,pre,value;

int input(int *post , int *ind)
{
    int i,len;  char ch;
    i=0;
    while(1)
    {
        if(scanf("%d",&ind[i++])==EOF) return 0; 
        ch=getchar(); if(ch=='\n')  break;
    }
    i=0;
    while(1)
    {
        if(scanf("%d",&post[i++])==EOF) return 0; 
        ch=getchar(); if(ch=='\n')  break;
    }
    return len=i;
}
int find(int len , int *s2 ,int key)
{
    int i;
    for(i=0; i<len; i++)  if(s2[i]==key)  return i;
    return i;
}
void build_treenode_post_and_ind(int len , int *s1 , int *s2 , struct treenode *tree , int mark , int level)
{
    int x,y,p;
    if(len<=0)
    {
        x=flag-start;
        if(mark==1)  tree[x].lchild=-1;
        if(mark==2)  tree[x].rchild=-1;
        return ;
    }
    x=flag-start;  y=s1+len-1-start;  
tree[y].data=s1[len-1]; tree[y].level=level; level++;
    if(mark==1)            tree[x].lchild=y;
    else if(mark==2)    tree[x].rchild=y;
    p=find(len,s2,s1[len-1]);  
    flag=s1+len-1;  mark=1;
    build_treenode_post_and_ind(p,s1,s2,tree,mark,level);
    flag=s1+len-1; mark=2;
    build_treenode_post_and_ind(len-p-1,s1+p,s2+p+1,tree,mark,level);
}
void DFS(struct treenode *tree , int s , int sum)
{
    int L,R;
    if(s<0)  
    {
        if( (tree[pre].lchild==-1 && tree[pre].rchild==-1) && 
( sum<min || (sum==min && tree[pre].data<value) )  )
        { min=sum; leaf=pre; value=tree[pre].data; }
        return ;
    }
    else 
    {
        sum+=tree[s].data;  L=tree[s].lchild; R=tree[s].rchild;
        pre=s;  DFS(tree,L,sum);
        pre=s;    DFS(tree,R,sum);
    }
}
int main()
{
    int i,len,level,mark,sum; int post[MAX],ind[MAX];  struct treenode tree[MAX];
    while(1)
    {
        len=input(post , ind);    if(!len) return 0;
        start=post; flag=NULL; mark=0; level=0;
tree[0].lchild=tree[0].rchild=tree[0].level=-1; tree[0].data=0;
        build_treenode_post_and_ind(len,post ,ind ,tree,mark,level);
        min=INF; sum=0; leaf=pre=len-1; value=tree[len-1].data; i=len-1;  
        //leaf保存最后的答案中叶子结点在树结点数组中的下标，valua是记录当最短路径长度一样
//叶子结点的最小值，pre是记录前驱的下标，i是根结点下标
        DFS(tree,i,sum);  //把整个树的结点数组，根结点的下标和当前的总和传过去

        printf("%d\n",tree[leaf].data);
    }
    return 0;
}