Task: Chemical calculator


C++: #include <iomanip>
#include <iostream>
#include <map>
#include <string>
#include <vector>

std::map<std::string, double> atomicMass = {
    {"H", 1.008},
    {"He",    4.002602},
    {"Li",    6.94},
    {"Be",    9.0121831},
    {"B",    10.81},
    {"C",    12.011},
    {"N",    14.007},
    {"O",    15.999},
    {"F",    18.998403163},
    {"Ne",   20.1797},
    {"Na",   22.98976928},
    {"Mg",   24.305},
    {"Al",   26.9815385},
    {"Si",   28.085},
    {"P",    30.973761998},
    {"S",    32.06},
    {"Cl",   35.45},
    {"Ar",   39.948},
    {"K",    39.0983},
    {"Ca",   40.078},
    {"Sc",   44.955908},
    {"Ti",   47.867},
    {"V",    50.9415},
    {"Cr",   51.9961},
    {"Mn",   54.938044},
    {"Fe",   55.845},
    {"Co",   58.933194},
    {"Ni",   58.6934},
    {"Cu",   63.546},
    {"Zn",   65.38},
    {"Ga",   69.723},
    {"Ge",   72.630},
    {"As",   74.921595},
    {"Se",   78.971},
    {"Br",   79.904},
    {"Kr",   83.798},
    {"Rb",   85.4678},
    {"Sr",   87.62},
    {"Y",    88.90584},
    {"Zr",   91.224},
    {"Nb",   92.90637},
    {"Mo",   95.95},
    {"Ru",  101.07},
    {"Rh",  102.90550},
    {"Pd",  106.42},
    {"Ag",  107.8682},
    {"Cd",  112.414},
    {"In",  114.818},
    {"Sn",  118.710},
    {"Sb",  121.760},
    {"Te",  127.60},
    {"I",   126.90447},
    {"Xe",  131.293},
    {"Cs",  132.90545196},
    {"Ba",  137.327},
    {"La",  138.90547},
    {"Ce",  140.116},
    {"Pr",  140.90766},
    {"Nd",  144.242},
    {"Pm",  145},
    {"Sm",  150.36},
    {"Eu",  151.964},
    {"Gd",  157.25},
    {"Tb",  158.92535},
    {"Dy",  162.500},
    {"Ho",  164.93033},
    {"Er",  167.259},
    {"Tm",  168.93422},
    {"Yb",  173.054},
    {"Lu",  174.9668},
    {"Hf",  178.49},
    {"Ta",  180.94788},
    {"W",   183.84},
    {"Re",  186.207},
    {"Os",  190.23},
    {"Ir",  192.217},
    {"Pt",  195.084},
    {"Au",  196.966569},
    {"Hg",  200.592},
    {"Tl",  204.38},
    {"Pb",  207.2},
    {"Bi",  208.98040},
    {"Po",  209},
    {"At",  210},
    {"Rn",  222},
    {"Fr",  223},
    {"Ra",  226},
    {"Ac",  227},
    {"Th",  232.0377},
    {"Pa",  231.03588},
    {"U",   238.02891},
    {"Np",  237},
    {"Pu",  244},
    {"Am",  243},
    {"Cm",  247},
    {"Bk",  247},
    {"Cf",  251},
    {"Es",  252},
    {"Fm",  257},
    {"Uue", 315},
    {"Ubn", 299},
};

double evaluate(std::string s) {
    s += '[';

    double sum = 0.0;
    std::string symbol;
    std::string number;

    for (auto c : s) {
        if ('@' <= c && c <= '[') {
            
            int n = 1;
            if (number != "") {
                n = stoi(number);
            }
            if (symbol != "") {
                sum += atomicMass[symbol] * n;
            }
            if (c == '[') {
                break;
            }
            symbol = c;
            number = "";
        } else if ('a' <= c && c <= 'z') {
            symbol += c;
        } else if ('0' <= c && c <= '9') {
            number += c;
        } else {
            std::string msg = "Unexpected symbol ";
            msg += c;
            msg += " in molecule";
            throw std::runtime_error(msg);
        }
    }

    return sum;
}

std::string replaceFirst(const std::string &text, const std::string &search, const std::string &replace) {
    auto pos = text.find(search);
    if (pos == std::string::npos) {
        return text;
    }

    auto beg = text.substr(0, pos);
    auto end = text.substr(pos + search.length());
    return beg + replace + end;
}

std::string replaceParens(std::string s) {
    char letter = 'a';
    while (true) {
        auto start = s.find("(");
        if (start == std::string::npos) {
            break;
        }

        for (size_t i = start + 1; i < s.length(); i++) {
            if (s[i] == ')') {
                auto expr = s.substr(start + 1, i - start - 1);
                std::string symbol = "@";
                symbol += letter;
                auto search = s.substr(start, i + 1 - start);
                s = replaceFirst(s, search, symbol);
                atomicMass[symbol] = evaluate(expr);
                letter++;
                break;
            }
            if (s[i] == '(') {
                start = i;
                continue;
            }
        }
    }
    return s;
}

int main() {
    std::vector<std::string> molecules = {
        "H", "H2", "H2O", "H2O2", "(HO)2", "Na2SO4", "C6H12",
        "COOH(C(CH3)2)3CH3", "C6H4O2(OH)4", "C27H46O", "Uue"
    };
    for (auto molecule : molecules) {
        auto mass = evaluate(replaceParens(molecule));
        std::cout << std::setw(17) << molecule << " -> " << std::setw(7) << std::fixed << std::setprecision(3) << mass << '\n';
    }

    return 0;
}







VB: Module Module1

    Dim atomicMass As New Dictionary(Of String, Double) From {
        {"H", 1.008},
        {"He", 4.002602},
        {"Li", 6.94},
        {"Be", 9.0121831},
        {"B", 10.81},
        {"C", 12.011},
        {"N", 14.007},
        {"O", 15.999},
        {"F", 18.998403163},
        {"Ne", 20.1797},
        {"Na", 22.98976928},
        {"Mg", 24.305},
        {"Al", 26.9815385},
        {"Si", 28.085},
        {"P", 30.973761998},
        {"S", 32.06},
        {"Cl", 35.45},
        {"Ar", 39.948},
        {"K", 39.0983},
        {"Ca", 40.078},
        {"Sc", 44.955908},
        {"Ti", 47.867},
        {"V", 50.9415},
        {"Cr", 51.9961},
        {"Mn", 54.938044},
        {"Fe", 55.845},
        {"Co", 58.933194},
        {"Ni", 58.6934},
        {"Cu", 63.546},
        {"Zn", 65.38},
        {"Ga", 69.723},
        {"Ge", 72.63},
        {"As", 74.921595},
        {"Se", 78.971},
        {"Br", 79.904},
        {"Kr", 83.798},
        {"Rb", 85.4678},
        {"Sr", 87.62},
        {"Y", 88.90584},
        {"Zr", 91.224},
        {"Nb", 92.90637},
        {"Mo", 95.95},
        {"Ru", 101.07},
        {"Rh", 102.9055},
        {"Pd", 106.42},
        {"Ag", 107.8682},
        {"Cd", 112.414},
        {"In", 114.818},
        {"Sn", 118.71},
        {"Sb", 121.76},
        {"Te", 127.6},
        {"I", 126.90447},
        {"Xe", 131.293},
        {"Cs", 132.90545196},
        {"Ba", 137.327},
        {"La", 138.90547},
        {"Ce", 140.116},
        {"Pr", 140.90766},
        {"Nd", 144.242},
        {"Pm", 145},
        {"Sm", 150.36},
        {"Eu", 151.964},
        {"Gd", 157.25},
        {"Tb", 158.92535},
        {"Dy", 162.5},
        {"Ho", 164.93033},
        {"Er", 167.259},
        {"Tm", 168.93422},
        {"Yb", 173.054},
        {"Lu", 174.9668},
        {"Hf", 178.49},
        {"Ta", 180.94788},
        {"W", 183.84},
        {"Re", 186.207},
        {"Os", 190.23},
        {"Ir", 192.217},
        {"Pt", 195.084},
        {"Au", 196.966569},
        {"Hg", 200.592},
        {"Tl", 204.38},
        {"Pb", 207.2},
        {"Bi", 208.9804},
        {"Po", 209},
        {"At", 210},
        {"Rn", 222},
        {"Fr", 223},
        {"Ra", 226},
        {"Ac", 227},
        {"Th", 232.0377},
        {"Pa", 231.03588},
        {"U", 238.02891},
        {"Np", 237},
        {"Pu", 244},
        {"Am", 243},
        {"Cm", 247},
        {"Bk", 247},
        {"Cf", 251},
        {"Es", 252},
        {"Fm", 257},
        {"Uue", 315},
        {"Ubn", 299}
    }

    Function Evaluate(s As String) As Double
        s += "["
        Dim sum = 0.0
        Dim symbol = ""
        Dim number = ""
        For i = 1 To s.Length
            Dim c = s(i - 1)
            If "@" <= c AndAlso c <= "[" Then
                
                Dim n = 1
                If number <> "" Then
                    n = Integer.Parse(number)
                End If
                If symbol <> "" Then
                    sum += atomicMass(symbol) * n
                End If
                If c = "[" Then
                    Exit For
                End If
                symbol = c.ToString
                number = ""
            ElseIf "a" <= c AndAlso c <= "z" Then
                symbol += c
            ElseIf "0" <= c AndAlso c <= "9" Then
                number += c
            Else
                Throw New Exception(String.Format("Unexpected symbol {0} in molecule", c))
            End If
        Next
        Return sum
    End Function

    Function ReplaceFirst(text As String, search As String, replace As String) As String
        Dim pos = text.IndexOf(search)
        If pos < 0 Then
            Return text
        Else
            Return text.Substring(0, pos) + replace + text.Substring(pos + search.Length)
        End If
    End Function

    Function ReplaceParens(s As String) As String
        Dim letter = "s"c
        While True
            Dim start = s.IndexOf("(")
            If start = -1 Then
                Exit While
            End If

            For i = start + 1 To s.Length - 1
                If s(i) = ")" Then
                    Dim expr = s.Substring(start + 1, i - start - 1)
                    Dim symbol = String.Format("@{0}", letter)
                    s = ReplaceFirst(s, s.Substring(start, i + 1 - start), symbol)
                    atomicMass(symbol) = Evaluate(expr)
                    letter = Chr(Asc(letter) + 1)
                    Exit For
                End If
                If s(i) = "(" Then
                    start = i
                    Continue For
                End If
            Next
        End While
        Return s
    End Function

    Sub Main()
        Dim molecules() As String = {
            "H", "H2", "H2O", "H2O2", "(HO)2", "Na2SO4", "C6H12",
            "COOH(C(CH3)2)3CH3", "C6H4O2(OH)4", "C27H46O", "Uue"
        }
        For Each molecule In molecules
            Dim mass = Evaluate(ReplaceParens(molecule))
            Console.WriteLine("{0,17} -> {1,7:0.000}", molecule, mass)
        Next
    End Sub

End Module