HDU 1622

http://acm.hdu.edu.cn/showproblem.php?pid=1622

白书上6.3.2二叉树层次遍历的例题，层次遍历用bfs，建立二叉树，很基础的题目

#include <iostream>

#include <cstdio>

#include <cstdlib>

#include <cstring>

#include <queue>



using namespace std;



struct node{

    int vis,v;

    node *l,*r;

};



node *root;



node* newnode(){

    node *u=new node;

    if(u!=NULL){

        u->vis=0;

        u->l=u->r=NULL;

    }

    return u;

}



int failed;



void addnode(int v,char* s){

    int len=strlen(s);

    node* u=root;

    for(int i=0;i<len;i++){

        if(s[i]=='L'){

            if(u->l==NULL)u->l=newnode();

            u=u->l;

        }

        else if(s[i]=='R'){

            if(u->r==NULL)u->r=newnode();

            u=u->r;

        }

    }

    if(u->vis)failed=1;

    u->v=v;

    u->vis=1;

}



char s[305];



void remove_tree(node* u){

    if(u==NULL)return;

    remove_tree(u->l);

    remove_tree(u->r);

    delete u;

}



int input(){

    failed=0;

    remove_tree(root);

    root=newnode();

    while(1){

        if(scanf("%s",s)==EOF)return 0;

        if(!strcmp(s,"()"))break;

        int v;

        sscanf(&s[1],"%d",&v);

        addnode(v,strchr(s,',')+1);

    }

    return 1;

}



int st,ans[305];



int bfs(){

    queue <node*> q;

    q.push(root);

    while(!q.empty()){

        node* u=q.front();

        q.pop();

        if(u->vis==0)return 0;

        ans[st++]=u->v;

        if(u->l!=NULL)q.push(u->l);

        if(u->r!=NULL)q.push(u->r);

    }

    return 1;

}



int main(){

    while(input()){

        if(failed)puts("not complete");

        else{

            st=0;

            if(!bfs())puts("not complete");

            else{

                for(int i=0;i<st;i++){

                    if(!i)

                        printf("%d",ans[i]);

                    else 

                        printf(" %d",ans[i]);

                }

                putchar('\n');

            }

        }

    }

    return 0;

}

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