C++ Basic Battle System

#include <iostream>
#include <cmath>
#include <cstdlib>
#include <ctime>

int main() {
    //Challenge: Make a battle system where an enemy HP is slowly depleted by attacks.

    double hp = 500;
    int atk;
    double power;
    double damage;
    int atkAmt = 0;
    double accuracy;
    int random1;
    int random2;
    double accuracyHit;
    srand(time(NULL));

    do{
        std::cout << "Enter an Attack Number Between 1-100: ";
        std::cin >> atk;
        //if(atk <= 0) atk = 1;
        //else if(atk > 100) atk = 100;
    }while(atk > 100 || atk <= 0);

    //accuracy will go down to 80 if atk=100 and 100 if atk=1.
    accuracy = (-20 * atk + 9920)/99;

    //atk 1 base 30 atk 100 base 150
    // y = (120x + 2850) / 99
    power = (120 * atk + 2850) / 99;

    do{
        std::cout << "Enemy HP: " << round(hp) << '\n';

        //Accuracy Check
        random1 = rand() % 100 + 1;

        if(random1 > accuracy) {
            //Miss Chance
            std::cout << "You missed! ";
        }

        else{
            //Damage Calcs
            random2 = rand() % 41 + 80; //Goes from 0.8 to 1.2
            if(random2 == 120) {
                //Crits
                damage = power * 1.5;
                std::cout << "**Critical Hit!**\n";
                std::cout << "You did " << damage << " damage! ";
            }
            else {
                damage = round(power * ((double)random2 / 100));
                std::cout << "You did " << damage << " damage! ";
            }

            //HP Removal
            hp = hp - damage;
        }

        //Turn Track
        atkAmt++;
    }while(hp > 0);

    std::cout << "Enemy defeated!\nTook " << atkAmt << " turns to defeat!";

    return 0;
}