Cod sursa(job #2334684)

Utilizator triscacezarTrisca Vicol Cezar triscacezar Data 2 februarie 2019 21:19:41
Problema Evaluarea unei expresii Scor 40
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.59 kb
#include <bits/stdc++.h>

using namespace std;

ifstream f("evaluare.in");
ofstream g("evaluare.out");

int n,i;
string s;
vector<pair<int,int> > pst;
stack<int> St;
map<char,int> Map;

int termen()
{
    int ret=0;
    for(;i<n&&'0'<=s[i]&&s[i]<='9';i++)
        ret=ret*10+(s[i]-'0');
    return ret;
}

int main()
{
    f>>s;n=s.size();
    Map['-']=1;
    Map['+']=2;
    Map['*']=3;
    Map['/']=4;
    for(i=0;i<n;)
    {
        if('0'<=s[i]&&s[i]<='9')
        {
            pst.push_back({termen(),0});
            continue;
        }
        if(s[i]=='('){St.push(5);i++;continue;}
        if(s[i]==')')
        {
            while(St.top()!=5)
            {
                pst.push_back({0,St.top()});
                St.pop();
            }St.pop();
            i++;continue;
        }
        while(St.size()&&(St.top()>=Map[s[i]])&&(St.top()!=5))
        {
            pst.push_back({0,St.top()});
            St.pop();
        }
        St.push(Map[s[i]]);
        i++;
    }
    while(St.size())
    {
        pst.push_back({0,St.top()});
        St.pop();
    }
//    for(auto it:pst)
//        g<<it.first<<' '<<it.second<<'\n';
    for(auto it:pst)
        if(!it.second)
            St.push(it.first);
        else
        {
            int op1=St.top();St.pop();
            int op2=St.top();St.pop();
            if(it.second==2)St.push(op2+op1);
            if(it.second==1)St.push(op2-op1);
            if(it.second==3)St.push(op2*op1);
            if(it.second==4)St.push(op2/op1);
        }
    g<<St.top();
    return 0;
}