구름 코테 6주차

// 1번
// Run by Node.js
const readline = require('readline');

(async () => {
	let rl = readline.createInterface({ input: process.stdin });
	
	let count = 0
	rl.on('line', (line) => {
		if (count++ === 6) rl.close()
		solution(line.trim())
	})
	
	rl.on('close', () => {
		process.exit()	
	})
	
	
})();

function solution(string) {
	const digits = string.split('').map(Number)
	
	const oddSumUnit = digits
		.flatMap((digit, index) => index % 2 ? [] : [digit])
		.reduce((a,b) => a + b) % 10
	
	const evenMulUnit = digits.flatMap((digit, index) => index % 2 && digit !== 0 ? [digit] : []).reduce((a,b) => ((a % 10) * (b % 10) % 10), 1)
	const result = (oddSumUnit * evenMulUnit) % 10
	console.log(result)
}

// 2번
// Run by Node.js
const readline = require('readline');

(async () => {
    let rl = readline.createInterface({ input: process.stdin });

    let count = 0
    let length
    let cipher

    rl.on('line', (line) => {
        if (count++ === 2) rl.close()
        if (count === 1) {
            length = Number(line.trim())
        } else if (count === 2) {
            cipher = line.trim()
            solution(cipher)
        }
    })

    rl.on('close', () => {
      process.exit();
    })
})();

function solution(cipher) {
    const alphabet = cipher.split('').flatMap((char, index) => index % 2 ? [] : [char])
    const actionCount = cipher.split('').flatMap((char, index) => index % 2 ? [(Number(char) ** 2) % 26] : [])


    const result = alphabet.map((char, index) => {
        const charCode = (char.charCodeAt() + actionCount[index] -  97) % 26 + 97

        return String.fromCharCode(charCode)
    }).join('')

    console.log(result)
}

// 3번 
// Run by Node.js
const readline = require('readline');

(async () => {
    let rl = readline.createInterface({ input: process.stdin });

    let index = 0
    let testCount
    let testCase = []

    rl.on('line', (line) => {
        index++
        if (index === 1) {
            testCount = Number(line.trim())
            return
        }
        testCase.push(line.trimEnd())
        if (index % 2) {
            solution(testCase)
            testCase = []
        }

        if (index === testCount * 2 + 1) rl.close()
    })

    rl.on('close', () => {
        process.exit();
    })
})();

function solution([first, second]) {
    const target = first
    const [flag, token] = second.split(' ')

    const isEncryption = flag === 'E'
    const repeatCount = Math.ceil(target.length / token.length)
    const validToken = token.repeat(repeatCount).slice(0, target.length)

    const COUNT_ALPHABET = 26
    const code = validToken.split('').map(char => char.charCodeAt() % COUNT_ALPHABET)
    const isSmallAlphabet = (char) => 'a'.charCodeAt() <= char.charCodeAt() && char.charCodeAt() < 'a'.charCodeAt() + COUNT_ALPHABET
    const isLargeAlphabet = (char) => 'A'.charCodeAt() <= char.charCodeAt() && char.charCodeAt() < 'A'.charCodeAt() + COUNT_ALPHABET
    const isAlphabet = (char) => isLargeAlphabet(char) || isSmallAlphabet(char)


    const encrypt = (targetChar, countShift) => {
        const startCharCode = isSmallAlphabet(targetChar) ? 'a'.charCodeAt() : 'A'.charCodeAt()
        const charCode = (targetChar.charCodeAt() - startCharCode + countShift) % COUNT_ALPHABET + startCharCode
        return String.fromCharCode(charCode)
    }

    const decrypt = (targetChar, countShift) => {
        const startCharCode = isSmallAlphabet(targetChar) ? 'a'.charCodeAt() : 'A'.charCodeAt()
        const charCode = (targetChar.charCodeAt() - startCharCode + 26 - countShift) % COUNT_ALPHABET + startCharCode
        return String.fromCharCode(charCode)
    }

    const result = target.split('').map((char, index) => {
        if (isAlphabet(char)) return isEncryption ? encrypt(char, code[index]) : decrypt(char, code[index])
        else  return char
    }).join('')

    console.log(result)
}