Cod sursa(job #1826714)

Utilizator pibogaBogdan piboga Data 10 decembrie 2016 19:57:08
Problema Evaluarea unei expresii Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.81 kb
#include <fstream>
#include <cstring>

using namespace std;

ifstream fin ("evaluare.in");
ofstream fout("evaluare.out");

char c[100010],a[100010],k;
int b[100010],vl[260];
int x,y,i,n,d;
bool ok;

bool nr()
{
    if (c[i]>='0' && c[i]<='9') return 1;
    return 0;
}

bool op()
{
    if (k=='+' ||
    k=='-' ||
    k=='*' ||
    k=='/' )
        return 1;
    return 0;
}

void tr()
{
    int m;int n;
    m=b[y-1]; n=b[y];
    --y;
    switch (a[x])
    {
        case '+' : { b[y]=m+n ; break; }
        case '-' : { b[y]=m-n ; break; }
        case '*' : { b[y]=m*n ; break; }
        case '/' : { b[y]=m/n ; break; }
    }
    --x;

}

int main()
{
    fin.getline (c+1,100010);

    n=strlen(c+1);

    //vl['(']=1;
    vl['+']=vl['-']=2;
    vl['*']=vl['/']=3;

    c[0]='(';
    c[n+1]=')';

    for (i=0;i<=n+1;++i)
    {
        k=c[i];
        if (nr())
        {
            d=k-'0';
            ++i;
            while (nr())
            {
                d*=10;
                d+=(c[i]-'0');
                ++i;
            }
            --i;
            b[++y]=d;
        }

        else

        if (op())
        {

            if (vl[c[i]] <= vl[a[x]])
            {

                tr();
                --i;

            }
            else
            {
                a[++x]=c[i];
            }
        }

        else
        if (c[i]=='(')
        {
            a[++x]=c[i];
            ++i;
            while (c[i]=='(')
            {
                a[++x]=c[i];
                ++i;
            }
            --i;
        }

        else
        {
            while (a[x]!='(')
            {
                tr();
            }
            --x;
        }


    }

    fout << b[1];

    return 0;
}