Cod sursa(job #527749)

Utilizator BlaugranasEnal Gemaledin Blaugranas Data 1 februarie 2011 10:12:52
Problema Evaluarea unei expresii Scor 60
Compilator cpp Status done
Runda Arhiva educationala Marime 2.72 kb
#include<iostream.h>
#include<fstream.h>
#include<string.h>
#define N 100001
typedef struct stack
{char st[N];
long sp;};
typedef struct stiva
{long v[N],n;};
char inf[N],postf[N];
long i,j;

void add(stiva &s,long nr)
{s.v[++s.n]=nr;}

long del(stiva &s)
{return s.v[s.n--];}

void push(stack &s,char ch)
{s.st[++s.sp]=ch;}

char pop(stack &s)
{return s.st[s.sp--];}

char top(stack s)
{return s.st[s.sp];}

int isNumber(char ci[N])
{long i;
for(i=0;i<strlen(ci);i++)
if(ci[i]<'0'||ci[i]>'9')
       return 0;
return 1;}

long eval(char postf[N])
{stiva q;
char *ci;
long i=0,t1,t2;
q.n=0;
ci=strtok(postf," ");
while(ci!=NULL)
       {if(isNumber(ci)==1)
             add(q,atol(ci));
       else
             {if(*ci=='+')
                    {t2=del(q);
                    t1=del(q);
                    add(q,t1+t2);}
             else
                    if(*ci=='-')
                            {t2=del(q);
                            t1=del(q);
                            add(q,t1-t2);}
                    else
                            if(*ci=='*')
                                    {t2=del(q);
                                    t1=del(q);
                                    add(q,t1*t2);}
                            else
                                    if(*ci=='/')
                                            {t2=del(q);
                                            t1=del(q);
                                            add(q,t1/t2);}}
       ci=strtok(NULL," ");}
return del(q);}

int pri(char ch)
{if(ch=='(')
       return 0;
else
       if(ch=='+'||ch=='-')
              return 1;
       else
              return 2;}

void topostf(char in[N],char out[N])
{stack s;
s.sp=0;
long i=0,j=0,r;
while(i<strlen(in))
       {if(in[i]>='0'&&in[i]<='9')
              {while(in[i]>='0'&&in[i]<='9')
                    out[j++]=in[i++];
              i--;}
       else
              {out[j++]=' ';
              if(in[i]=='(') 
                      push(s,in[i]);
              else
                      if(in[i]==')')
                           {while(s.sp!=0&&((r=pop(s))!='('))
                                 {out[j++]=r;
                                 out[j++]=' ';}}
                      else
                           {while(s.sp!=0&&pri(in[i])<=pri(top(s)))
                                 {out[j++]=pop(s);
                                 out[j++]=' ';}
                           push(s,in[i]);}}
       i++;}
while(s.sp!=0)
      {out[j++]=pop(s);
      out[j++]=' ';}
out[j]='\0';}

int main()
{ifstream f1("evaluare.in");
ofstream f2("evaluare.out");
f1>>inf;
topostf(inf,postf);
f2<<eval(postf);
f1.close();
f2.close();
return 0;}