poj 1911 A Well

#include <cstdio>#include <cstdlib>#include <cstring>#include <cctype>#include <string>#include <set>#include <stack> #include <iostream>#include <algorithm>using namespace std;#define ERROR non=true;returnset<string> used;stack<string> s;bool non, root;bool gettag(char* &ch, string &tag, bool &end, bool ∅){    int p1, p2, p3, p4;    string attribute;    end=false, empty=false;    tag=attribute="";    ch++;  //get tag    if (*ch=='/'){end=true;ch++;}    while (isalnum(*ch) || *ch=='-')          {        tag+=*ch;        ch++;    }    while (isspace(*ch)) ch++;    if (*ch=='>')      //end of tag?        return 1;    if (*ch=='/')    {        int cal=0;        ch++;        while (*ch!='>'){cal++;ch++;}        if (cal>0) return -2;        if (end) return -1;        else empty=true;    }    while (isalnum(*ch) || *ch=='-' || *ch=='.' || *ch=='"' || *ch=='=')        //get attribute    {        attribute+=*ch;        ch++;    }    if (attribute.length()>0)    {        p1=attribute.find("=", 0);      if (p1==-1) return -3;        p2=attribute.find(""", 0);     if (p2<p1) return -4;        p2=attribute.find(""", p1+1);  if (p2==-1) return -5;        p3=attribute.find(""", p2+1);  if (p3==-1 || p3==p2+1) return -6;   //empty value        p4=attribute.find(""", p3+1);  if (p4!=-1) return -7;    //extra "        p4=attribute.find("=", p1+1);   if (p4!=-1) return -8;    //extra =    }    while (isspace(*ch)) ch++;    if (*ch=='>') return 1;    if (*ch=='/')    {        int cal=0;        ch++;        while (*ch!='>'){cal++;ch++;}        if (cal>0) return -10;        if (end) return -9;        else empty=true;    }    while (*ch!='>'){        ch++;        if (!isspace(*ch) && *ch!='>') return -11;    }    return 1;}void solve(char *ch){    bool end, empty;    string tag;    int tmp;    while (!non && *ch!='')    {        if (*ch=='<')        { tmp=gettag(ch, tag, end, empty); if (tmp==1) {     if (end && empty){         ERROR;     }     if (empty && used.count(tag)>0){         ERROR;     }     else if (!empty && !end)     {         if (used.count(tag)>0){  ERROR;         }         if (s.empty())         {  if (root){ERROR;}  else root=true;         }         used.insert(tag);         s.push(tag);     }     else if (!empty && end)     {         if (s.empty() || s.top()!=tag){         ERROR;     }         used.erase(tag);         s.pop();     } } else{ERROR;}        }        else ch++;    }}int main(){    string tag, attribute;    bool firstdata=true;    bool end, empty;    char buf[65536];    do{        while (gets(buf)!=NULL && strcmp(buf, "<?xml version="1.0"?>")!=0     && strcmp(buf, "<?end?>n")!=0)        { solve(buf);        }        if (strcmp(buf, "<?xml version="1.0"?>")==0)        { if (!firstdata) {     if (non || !s.empty()) printf("non well-formedn");     else printf("well-formedn"); } else firstdata=false; non=false; root=false; used.clear(); while (!s.empty()) s.pop();        }    }while (strcmp(buf, "<?end?>")!=0);    if (non || !s.empty()) printf("non well-formedn");    else printf("well-formedn");    return 0;}