uva548 （建树）二种方式实现 简单易懂

数组实现

#include <iostream>#include <sstream>#include <string>#define maxn 10000+10using namespace std;int inorder[maxn],post[maxn],lch[maxn],rch[maxn];int n;bool read(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[R2];    int p=L1;    while(inorder[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_sum,best;void dfs(int u,int sum ){  sum+=u;  if(!lch[u]&&!rch[u])  {    if(best_sum>sum||(best_sum==sum&&u<best))    {        best_sum=sum;        best=u;    }  }  if(lch[u])dfs(lch[u],sum);  if(rch[u])dfs(rch[u],sum);}int main(){    while(read(inorder))    {        read(post);        build(0,n-1,0,n-1);        best_sum=1000000000;        dfs(post[n-1],0);        cout<<best<<endl;    }    return 0;}

指针实现

#include <iostream>#include <stdio.h>#include <stdlib.h>#define maxn 10000+10using namespace std;int Inorder[maxn],Post[maxn];int cnt,ans;int best_sum,best;typedef struct BiNode{    int data;    struct BiNode *left,*right;} BiNode,*BiTree;//BiNode node[maxn];////BiTree NewNode()//{//    node[ans].left=NULL;//    node[ans].right=NULL;//    return &node[ans++];//}void input(){    cnt=1;    while(getchar()!='\n')        scanf("%d",&Inorder[cnt++]);    for(int i=-0; i<cnt; i++)        cin>>Post[i];}BiTree Creat(int *mid,int *post,int len){    if(len==0)        return NULL;    int p=len-1;    while(mid[p]!=post[len-1])--p;    //BiTree u=NewNode();    BiTree u=(BiTree)malloc(sizeof(BiNode));    u->data=post[len-1];    u->left=Creat(mid,post,p);    u->right=Creat(mid+p+1,post+p,len-p-1);    return u;}void dfs(BiTree T,int sum){    sum+=T->data;    if(!T->left&&!T->right)    {        if(sum<best_sum||(sum==best_sum&&T->data<best))        {            best_sum=sum;            best=T->data;        }    }    if(T->left)dfs(T->left,sum);    if(T->right)dfs(T->right,sum);}int main(){    while(cin>>Inorder[0])    {        //ans=0;        input();        BiTree root=NULL;        root=Creat(Inorder,Post,cnt);        best_sum=1000000000;        dfs(root,0);        cout<<best<<endl;    }    return 0;}