[백준 알고리즘] 1. 입출력과 사칙연산 / 2. if문 / 3. for문 / 4. while문

알고리즘 문제풀이를 시작하며..

단계별 풀이를 진행하며 초반에는 막힐 때마다 해당 내용에 대해 찾아보기로 하고

복잡한 알고리즘 문제를 풀기 전에는 내용에 대한 공부를 미리 하기로 한다.

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[ 10171 - 고양이 ]

 

swift5 이후 버전에서는 #와 "의 조합으로 특수문자 표현이 가능하다.

여러 줄의 문자열을 String으로 변환할 때는 따옴표 세개(""")를 사용한다.

let cat = #"""
\    /\
 )  ( ')
(  /  )
 \(__)|
"""#

 

 

[ 1000 - A+B ]

swift는 project파일이나 playground에서 입력을 받을 수 없다. (샌드박스(https://zeddios.tistory.com/432) 때문.. 추후 정리 예정)

command Line Tool에서 실행해야한다.

 

1. readLine() 함수(말 그대로 한 줄을 읽어오는 함수)를 통해 입력문자를 받을 수 있다.

2. 한 줄로 입력받은 숫자를 찢기 위해 split 또는 component(separatedBy: " ")를 사용한다. 

참고 :  https://pengcoder.tistory.com/31?category=427332 

  

import Foundation

let line = readLine()
if let line = line {
    var arr = line.components(separatedBy: " ")
    print(Int(arr[0])!+Int(arr[1])!)
}

 

 1008번

let line = readLine()
let arr = line?.split(separator: " ").map({Double($0)})

if let arr1 = arr?[0], let arr2 = arr?[1] {
    // print(arr1/arr2)
}

 10869번

let line  = readLine()
let arr = line?.split(separator: " ").map({Int($0)})
if let arr1 = arr?[0], let arr2 = arr?[1] {
    print(arr1+arr2)
    print(arr1-arr2)
    print(arr1*arr2)
    print(arr1/arr2)
    print(arr1%arr2)
}

 10430번
let line = readLine()
let arr = line?.split(separator: " ").map({Int($0)})
if let arr1 = arr?[0], let arr2 = arr?[1], let arr3 = arr?[2] {
    print((arr1+arr2)%arr3)
    print(((arr1%arr3) + (arr2%arr3))%arr3)
    print((arr1*arr2)%arr3)
    print(((arr1%arr3) * (arr2%arr3))%arr3)
}

 2588번 (8초)
let line = readLine()
let line2 = readLine()
let firstNum: Int
let secondNum: Int
if let lineText = line, let line2Text = line2 {
    firstNum = Int(lineText)!
    secondNum = Int(line2Text)!
    print(firstNum * ((secondNum%10)))
    print(firstNum * ((secondNum/10)%10))
    print(firstNum * ((secondNum/100)))
    print(firstNum*secondNum)
}

 2588번 - 2 (8초)
let line = Int(readLine()!)!
let line2 = Int(readLine()!)!
var line2Use = line2

while line2Use != 0 {
    print(line*(line2Use%10))
    line2Use /= 10
}
print(line * line2)

 1330번
let lineArr = readLine()?.split(separator: " ").map({Int($0)})
if lineArr![0]! > lineArr![1]! {
    print(">")
}
else if lineArr![0]! == lineArr![1]! {
    print("==")
}
else {
    print("<")
}

 9498번 (8초)
let line = Int(readLine()!)!
if line >= 90 {
    print("A")
}
else if line >= 80 {
    print("B")
}
else if line >= 70 {
    print("C")
}
else if line >= 60 {
    print("D")
}
else {
    print("F")
}

 9498번 - 2 (8초)
let line = Int(readLine()!)!
switch line {
case 90...100:
    print("A")
case 80...89:
    print("B")
case 70...79:
    print("C")
case 60...69:
    print("D")
default:
    print("F")
}

 2753번
let line = Int(readLine()!)!
if ((line%4 == 0) && (line%100 != 0)) || (line%400 == 0) {
    print("1")
}
else {
    print("0")
}

 14681번
let line = Int(readLine()!)!
let line2 = Int(readLine()!)!

if line > 0 && line2 > 0 {
    print("1")
}
else if line < 0 && line2 > 0 {
    print("2")
}
else if line < 0 && line2 < 0 {
    print("3")
}
else {
    print("4")
}

 2884번
let line = readLine()!.split(separator: " ").map({ Int($0)})
var a = line[0]!
var b = line[1]!

if b >= 45 {
    b -= 45
}
else {
    if a == 0 {
        a = 23
        b = b + 60 - 45
    }
    else {
        a -= 1
        b = b + 60 - 45
    }
}
print("\(a) \(b)")

 2739번
let line = Int(readLine()!)!
for i in 1...9 {
    print("\(line) * \(i) = \(line*i)")
}

 10950
let num = Int(readLine()!)!
for _ in 1...num {
    let line = readLine()!.split(separator: " ").map({Int($0)})
    print(line[0]! + line[1]!)
}

 8393번
let line = Int(readLine()!)!
var sum = 0
for i in 1...line {
    sum += i
}
print(sum)

 8393번 - 2
let line = Int(readLine()!)!
print((line*(line+1))/2)

 ------------------------------------------------------------------
 15552번 (시간초과 실패)
let line = Int(readLine()!)!
for _ in 1...line {
    let line2 = readLine()!.split(separator: " ").map({Int($0)})
    print(line2[0]! + line2[1]!)
}
 ------------------------------------------------------------------

 2741
let line = Int(readLine()!)!
for i in 1...line {
    print(i)
}

 2742
let line = Int(readLine()!)!
for i in 0...line-1 {
    print(line-i)
}

 2742 - 2
for i in stride(from: Int(readLine()!)!, to: 0, by: -1) {
    print(i)
}

 2742 - 3
let line = Int(readLine()!)!
let array = Array(1...line).reversed()
for i in array {
    print(i)
}

 11021
let line = Int(readLine()!)!
for i in 1...line {
    let line2 = readLine()!.split(separator: " ").map({Int($0)!})
    print("Case #\(i): \(line2[0] + line2[1])")
}

 11022
let line = Int(readLine()!)!
for i in 1...line {
    let line2 = readLine()!.split(separator: " ").map({Int($0)!})
    print("Case #\(i): \(line2[0]) + \(line2[1]) = \(line2[0] + line2[1])")
}

 2438
let line = Int(readLine()!)!
for i in 1...line {
    var str: String = ""
    for _ in 1...i {
        str.append("*")
    }
    print(str)
}

 2439 // 코드가 지저분해서 수정 에정. stride 함수, init에 대해 추가 예정
let line = Int(readLine()!)!
for i in 1...line {
    var str: String = ""
    if i != line {
        for _ in 1...line-i {
            str.append(" ")
        }
    }
    else {
    }
    for _ in 1...i {
        str.append("*")
    }
    print(str)
}

 2439 - 2
 stride를 사용한 경우
let line = Int(readLine()!)!
for i in 1...line {
    var str = ""
    for _ in stride(from: line, to: i, by: -1) {
        str.append(" ")
    }
    for _ in stride(from: 0, to: i, by: 1) {
        str.append("*")
    }
    print(str)
}

 2439 - 3
 print terminator
let line = Int(readLine()!)!
for i in 1...line {
    for _ in 0..<line-i {
        print(" ", terminator: "")
    }
    for _ in 1...i {
        print("*", terminator: "")
    }
    print("")
}

 2439 - 4
let line = Int(readLine()!)!
for i in 1...line {
    for _ in stride(from: 1, to: line+1-i, by: 1) {
        print(" ", terminator: "")
    }
    for _ in stride(from: 1, to: i+1, by: 1) {
        print("*", terminator: "")
    }
    print("")
}

 2439 - 5
let line = Int(readLine()!)!
for i in 1...line {
    for _ in 0..<line-i {
        print(" ", terminator: "")
    }
    for _ in 1..<i+1 {
        print("*", terminator: "")
    }
    print("")
}


 10871
let line = readLine()!.split(separator: " ").map({ Int( $0 )!})
let line2 = readLine()!.split(separator: " ").map({ Int( $0 )!})
for i in 0...line2.count-1 {
    if line2[i] < line[1] {
        print(line2[i], terminator: " ")
    }
}

 10871 - 2
let line = readLine()!.split(separator: " ").map( { Int($0)!} )
let line2 = readLine()!.split(separator: " ").map( { Int($0)!} )
let result = line2.filter( { $0 < line[1] } )
for i in 0...result.count-1 {
    print(result[i], terminator: " ")
}

 10871 - 3
let line = readLine()!.split(separator: " ").map( { Int($0)!} )
let line2 = readLine()!.split(separator: " ").map( { Int($0)!} )
let result = line2.filter( { $0 < line[1] } ).map({ "\($0)" }).joined(separator: " ")
print(result)

 10952
while true {
    let line = readLine()!.split(separator: " ").map({Int($0)!})
    if line[0] == 0 && line[1] == 0 {
        break
    }
    print(line[0] + line[1])
}

 10951
 EOF가 발생하면 readline은 false가 되고 반복이 break된다.
while let line = readLine() {
    let number = line.split(separator: " ").map({Int($0)!})
    print(number[0] + number[1])
}

 1110
 다시 풀기
var count: Int = 0
var number: Int = 0

var line = Int(readLine()!)!
let firstLine = line
while true {
    var leftNum = line/10
    var rightNum = line%10
    number = (leftNum + rightNum)%10 + rightNum*10
    line = number
    count += 1
    if firstLine == number {
        break
    }
}
print(count)