개발야옹

https://www.acmicpc.net/problem/10828

const fs = require('fs');
const input = fs.readFileSync('/dev/stdin').toString().trim().split("\n");

const N = Number(input[0]);
const stack = [];
const result = [];

for(let i = 0 ;i < N ; i++) {
    const command = input[i+1].split(" ");
    if(command[0] === 'push') {
        stack.push(Number(command[1]));
    } else if(command[0] === 'pop') {
        result.push(stack.length === 0 ? -1 : stack.pop());
    } else if(command[0] === 'size') {
        result.push(stack.length);
    } else if(command[0] === 'empty') {
        result.push(stack.length === 0 ? 1 : 0);
    } else if(command[0] === 'top'){
        result.push(stack.length === 0 ? -1 : stack[stack.length-1]);
    }
}

console.log(result.join("\n"));

https://www.acmicpc.net/problem/9012

const fs = require('fs');
const input = fs.readFileSync('/dev/stdin').toString().trim().split("\n");

const N = Number(input.shift());

for(let i = 0 ; i  < N ; i++) {
    const stack = [];
    let prev = '';
    if(input[i].length % 2 !== 0) console.log("NO");
    else {
        const arr = input[i].split("");
        arr.forEach((a, index) => {
           if(index === 0 && a === ')') {
               return false;
           } else {
               if(stack.length === 0) {
                   stack.push(a);
               } else {
                   prev = stack.pop();
                   if(!(prev === '(' && a === ')')) {
                       stack.push(prev);
                       stack.push(a);
                   }
               }
           }
        });
        if(stack.length === 0) console.log('YES');
        else console.log("NO")
    }
}