mellowg

https://www.acmicpc.net/problem/1712

const fs = require('fs');
const input = fs.readFileSync('/dev/stdin').toString().split(" ");
 
const A = Number(input[0]);
const B = Number(input[1]);
const C = Number(input[2]);
 
// B >= C 손익분기점 없음
if(B >= C) console.log(-1);
else {
    let D = Math.abs((A/(B-C))-1);
    console.log(Math.floor(D));
}

https://school.programmers.co.kr/learn/courses/30/lessons/120875

function solution(dots) {
    for(let i = 0 ; i < 3  ; i++){
        for(let  j = 0 ; j < 3 - i; j++) {
            const tmp1 = [dots[i], dots[i+j+1]];
            const tmp2 = dots.filter((d) => {
                return ![dots[i].join(""),dots[i+j+1].join("")].includes(d.join(""));
            });
            
            const inclination1 = Math.abs((tmp1[0][0] - tmp1[1][0])/(tmp1[0][1] - tmp1[1][1]));
            const inclination2 = Math.abs((tmp2[0][0] - tmp2[1][0])/(tmp2[0][1] - tmp2[1][1]));
            
            if(inclination1 === inclination2) {
                return 1;
            }
        }
    }
    
    return 0;
}

https://school.programmers.co.kr/learn/courses/30/lessons/120840

function factorial(n) {
    let result = 1;
    for(let i = 2 ; i <= n ; i++) {
        result *= i;
    }
    return result;
}

function solution(balls, share) {
    const n_ = factorial(balls); // n!
    const m_ = factorial(share); // m!
    const n_m = factorial(balls-share); // (n-m)!
    
    return Math.round((n_)/(n_m * m_));   
}

https://school.programmers.co.kr/learn/courses/30/lessons/120922

function solution(M, N) {
    var answer = 0;
    if(M === 1 && N === 1) return 0;
    
    return (M*N)-1;
}