PAT 1119. Pre- and Post-order Traversals (30)

来源：互联网发布：汽车cae软件编辑：程序博客网时间：2024/06/05 09:37
#include<iostream>#include<cstring>#include<cstdio>#include<cstdlib>using namespace std;int n,pre[35],post[35],flag=0;int ans[35],k;struct node{  int num;  struct node* left;  struct node* right;};struct node* build(struct node* t,int preleft,int preright,int postleft,int postright){//cout<<preleft<<' '<<preright<<' '<<postleft<<' '<<postright<<endl;  if((postright-postleft)!=(preright-preleft)) return t;  if((postright<postleft)||(preright<preleft)) return t;//  if(postright>n||postleft<0||preright>n||preleft<0) return t;    if(t==NULL){    struct node* p=(struct node*)malloc(sizeof(struct node));    if(p==NULL) return p;    p->num=pre[preleft];    p->left=NULL;    p->right=NULL;    t=p;   // free(p);  }  if(preleft<preright){    int len=0,mid,i;    for(i=postleft;i<postright;i++){      if(post[i]==pre[preleft+1]){        break;      }    }    len=i+1-postleft;    t->left=build(t->left,preleft+1,preleft+len,postleft,i);    len=postright-(i+1);    t->right=build(t->right,preright-len+1,preright,i+1,postright-1);  }  return t;}int level(struct node* t){//  cout<<t<<endl;  if(t==NULL) return 0;  if((t->left!=NULL&&t->right==NULL)||(t->left==NULL&&t->right!=NULL)){//    cout<<"No"<<endl;    flag=1;  }  if(t->left!=NULL){    level(t->left);  }//  cout<<t->num<<' ';  ans[k++]=t->num;  if(t->right!=NULL){    level(t->right);  }  return 0;}int main(){  int n;  flag=0;  cin>>n;  for(int i=0;i<n;i++){    cin>>pre[i];  }  for(int i=0;i<n;i++){    cin>>post[i];  }  struct node* t;  t=NULL;  t=build(t,0,n-1,0,n-1);  level(t);  if(flag){  cout<<"No"<<endl;    cout<<ans[0];    for(int i=1;i<k;i++){      cout<<" "<<ans[i];    }    cout<<endl;  }  else{    cout<<"Yes"<<endl;    cout<<ans[0];    for(int i=1;i<k;i++){      cout<<" "<<ans[i];    }    cout<<endl;  }  return 0;}
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