문제 링크 : Rings and Rods
/**
* @param {string} rings
* @return {number}
*/
var countPoints = function(rings) {
const rods = '0123456789'
let cnt = 0
for(let rod of rods) {
if( rings.includes(`R${rod}`) && rings.includes(`G${rod}`) && rings.includes(`B${rod}`) ) cnt ++
}
return cnt
};