Boss_attack_B

#include<bits/stdc++.h>
#define pb push_back
#define err (s.size() == 0x11 || s.size() == 0x0b)
using namespace std;


typedef enum{
    OPERATOR,
    INT,
    LINEENTER
} Symbol;


Symbol sym;
int t = 0 , num , only_int = 0 , aaa = 0;
char op;
bool error = 0 , error2 = 0 , error3 = 0 , zero = 0;
vector<string> p;
string s;


bool is_op( char c ){ return c == '+' || c == '-' || c == '*' || c == '/'; }
bool is_num( char c ){ return c >= '0' && c <= '9'; }

bool is_int(){
    int tmp = t;
    if( (s[t] == '+' || s[t] == '-') && is_num( s[t+1] ) ) return 1;
    else if( is_num( s[t] ) ) return 1;
    return 0;
}


Symbol peek(){
    while( s[t] == ' ' && ++t );
    if( is_int() ) return INT;
    else if( is_op( s[t] ) ) return OPERATOR;
    else if( s[t] == '\n' || s[t] == '\0' ) return LINEENTER;
}

int match( Symbol sym ){
    while( s[t] == ' ' && ++t );
    if( sym == OPERATOR ){
        op = s[t++];
        return 2147483647;
    }
    else if( sym == INT ){
        if( !is_int() ) error = 1;
        int neg = 1 , sum = 0;
        if( s[t] == '-' ) ++t , neg = -1;
        if( s[t] == '+' ) ++t;
        while( is_num( s[t] ) ){
            sum *= 10;
            sum += s[t++] - 48;
        }
        num = sum * neg;
    }
    else if( sym == LINEENTER ){
    }
}

bool ReadFormula(){
    stringstream ss;
    ss << s;
    string tmp;
    while( ss >> tmp ){
        for( int i = 0 ; i < tmp.size() ; ++i ){
            //cout << tmp[i] << endl;
            if( !is_op( tmp[i] ) && !is_num( tmp[i] ) ){
                int j = i - 1 , k = i + 1;
                bool bb = 1;
                while( !is_num( tmp[j] ) && !is_op( tmp[j] ) && j > -1 ) --j;
                if( is_num( tmp[j] ) ){
                    while( is_num( tmp[j] ) || ( (tmp[j] == '+' || tmp[j] == '-') && bb ) ) {
                        if( tmp[j] == '+' || tmp[j] == '-' ) bb = 0;
                        --j;
                    }
                }
                while( !is_num( tmp[k] ) && !is_op( tmp[k] ) && k < tmp.size() ) ++k;
                while( is_num( tmp[k] ) || is_op( tmp[k] ) ) ++k;
                cout << "Error: Unknown token ";
                for( int w = j + 1 ; w < k ; ++w ) cout << tmp[w];
                puts("");
                return 0;
            }
        }
    }
    return 1;
}

int exp(){
    if( peek() == INT ){
        match( INT );
        return num;
    }
    else if( peek() == OPERATOR ){
        //puts( "OPERA" );
        error2 = 1;
        match( OPERATOR );
        char o = op;
        int a , b;
        a = exp();
        b = exp();
        match( LINEENTER );
        if( b == 2147483647 ){
            if( o != '-' || o != '+' ) error = error3 = 1;
            if( o == '-' ) return a * -1;
            else return a;
        }
        //cout << a << o << b << endl;
        switch( o ){
            case '+':
                return a + b;
                break;
            case '-':
                return a - b;
                break;
            case '*':
                return a * b;
                break;
            case '/':
                if( !b ){
                    //printf( "aaa->%d error->%d error2->%d error3->%d only_int->%d zero -> %d\n" , aaa,error,error2,error3,only_int,zero );
                    if( !( error || only_int > 1 || aaa > 1 ) ) zero = 1;
                    return 0;
                }
                return a / b;
                break;
        }
    }
    else {
        //error = 1;
        return 2147483647;
        //puts( "exp error" );
    }
    return 0;
}

int exps(){
    if( peek() == OPERATOR || peek() == INT ){
        error2 = 0;
        ++aaa;
        int ans = exp();
        if( !error2 ) ++only_int;
        exps();
        return ans;
    }
    else{
        // LAMDA
    }
}

int prog(){
    if( peek() == OPERATOR || peek() == INT ){
        return exps();
    }
    else{
        error = 1;
        //puts( "prog error" );
    }
}


int EvalFormula(){
    return prog();
}

int main(){
    puts( "Welcome use our calculator!" );

    cout << "> ";
    while( getline( cin , s ) ){
        error = error2 = error3 = only_int = zero = aaa = t = 0;

        while( s[t] == ' ' && ++t );
        if( t == s.size() && cin.eof() ) break;

        if( s == "" ) {
            cout << "> ";
            continue;
        }

        if( !ReadFormula() ) {
            cout << "> ";
            continue;
        }

        int ans = EvalFormula();
        //printf( "aaa->%d error->%d error2->%d error3->%d only_int->%d zero -> %d\n" , aaa,error,error2,error3,only_int,zero );
        if( aaa > 1  ) {
            if( aaa == 2 && only_int == 1 && err ) puts( "Error: Divide by ZERO!" );
            else puts("Error: Illegal formula!");
        }
        else if( error || only_int > 1 && !zero ) puts("Error: Illegal formula!");
        else if( zero ) puts( "Error: Divide by ZERO!" );
        else{
            cout << ans << endl;
        }
        if( cin.eof() ) break;
        cout << "> ";
    }
    puts( "ByeBye~" );
    return 0;
}