HackerRank

colornode.cpp

#include <string>
#include <iostream>
#include <initializer_list>
 
enum struct Color {
    red,blue,orange,purple,green,black,yellow,invalid=-1
};
 
Color FromStringToColor(std::string const& str) {
    return ((str == "red")    ? Color::red    :
            (str == "blue")   ? Color::blue   :
            (str == "orange") ? Color::orange :
            (str == "purple") ? Color::purple :
            (str == "green")  ? Color::green  : 
            (str == "black")  ? Color::black  : 
            (str == "yellow") ? Color::yellow : Color::invalid);
}
 
struct ColorNode {
    std::string color;
    ColorNode* next = nullptr;
};
 
ColorNode** TailOf(ColorNode** n)
{
    while (n[0]) n = &n[0]->next;
    return n;
}
 
void Push(ColorNode*& n, std::string value)
{
    *TailOf(&n) = new ColorNode{value};
}
 
void Push(ColorNode*& n, std::initializer_list<std::string> v)
{
    ColorNode** tail = TailOf(&n);
    for (auto& c : v)
    {
        *tail = new ColorNode{c};
        tail = &(*tail)->next;
    }
}
 
ColorNode* PrioritizeColors(ColorNode* a, ColorNode* b) {
    ColorNode* temp = nullptr;
    
    while (a && b) {
        Color colorA = FromStringToColor(a->color);
        Color colorB = FromStringToColor(b->color);
        
        if (colorA == Color::invalid || colorB == Color::invalid) {
            return temp;
        }
        
        if (colorA == colorB) {
            Push(temp, { a->color, b->color });
            a = a->next;
            b = b->next;
        } else if (colorA < colorB) {
            Push(temp, a->color);
            a = a->next;
        } else {
            Push(temp, b->color);
            b = b->next;
        }
    }
    
    while (b) {
        Push(temp, b->color);
        b = b->next;
    }
    while (a) {
        Push(temp, a->color);
        a = a->next;
    }
    return temp;
}

int main() {
    ColorNode* a = nullptr, *b = nullptr;
    Push(a, {"red", "red", "orange", "green", "black"});
    Push(b, {"red", "blue", "purple", "green", "yellow"});
    
    ColorNode* c = PrioritizeColors(a, b);
    
    while (c) {
        std::cout << c->color << " ";
        c = c->next;
    }
}