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Cod sursa(job #614827)
#include <string>
#include <fstream>
#include <cstdlib>
#define LevMax 2
#define ERROR (-1<<29)
using namespace std;
string expresion;
string::const_iterator it, iend;
const string op[]={ "+-", "*/", "^" };
inline int eval( char op, int a, int b )
{
switch( op )
{
case '+' : return a+b;
case '-' : return a-b;
case '*' : return a*b;
case '/' : return a/b;
default : return ERROR;
}
}
int eval( int level )
{
int x=0;
if( level == LevMax )
{
if( '(' == *it )
{
++it;
x=eval(0);
++it;
}
else if( *it >= '0' && *it <= '9' )
for( x=0; it < iend && *it >= '0' && *it <= '9'; ++it )
x=x*10+*it-'0';
}
else for( x=eval(level+1); it < iend && string::npos != op[level].find(*it); )
{
char op=*it;
++it;
x=eval( op, x, eval(level+1) );
}
return x;
}
int main( void )
{
ifstream in( "evaluare.in" );
getline( in, expresion );
it=expresion.begin();
iend=expresion.end();
ofstream out( "evaluare.out" );
out<<eval(0)<<'\n';
return EXIT_SUCCESS;
}