CFR 697 B. Barnicle ( Ad hoc )

Problem - B - Codeforces
Silly I really failed this one in the real test. Should have calmed down and check all cases manually since there weren't many to come up.

void solve(){
    string s; cin >> s;

    int dec_pos = s.size();
    for( int i = 0; i < s.size(); ++i )
        if( s[ i ] == '.' )
            dec_pos = i;

    vi numbers, num_pos;
    for( int i = 0; i < s.size(); ++i ){
        if( s[ i ] == '.' ) continue;
        if( s[ i ] == 'e' ) break;
        numbers.push_back( s[ i ] - '0' );
        num_pos.push_back( i );
    }
    for( int i = numbers.size() - 1; i >= 0; --i ){
        if( numbers[ i ] != 0 or num_pos[ i ] < dec_pos ) break;
        else numbers.pop_back();
    }

    if( numbers.empty() ){
        cout << 0 << "\n";
        return;
    }

    int p_cnt = 0;
    for( int i = 0; i < s.size(); ++i ){
        if( s[ i ] != 'e' ) continue;
        for( int j = i + 1; j < s.size(); ++j )
            p_cnt = p_cnt * 10 + s[ j ] - '0';
        break;
    }

    if( numbers.size() == p_cnt + 1 ){
        for( int num : numbers )
            cout << num;
        return;
    }

    if( numbers.size() < p_cnt + 1 ){
        for( int num : numbers )
            cout << num;
        for( int i = 0; i < p_cnt + 1 - numbers.size(); ++i )
            cout << 0;
        return;
    }

    if( numbers.size() > p_cnt + 1 ){
        for( int i = 0; i <= p_cnt; ++i )
            cout << numbers[ i ];
        cout << '.';
        for( int i = p_cnt + 1; i < numbers.size(); ++i )
            cout << numbers[ i ];
        return;
    }
}