프로그래머스 소수 찾기, 프로그래머스 입국심사 (늘이)

2022/Sep/week_4/프로그래머스_Lv2_소수찾기_하늘이.swift

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+//
+//  main.swift
+//  Lv2_소수 찾기
+//
+//  Created by neuli on 2022/09/27.
+//
+
+import Foundation
+
+var result: Set<Int> = []
+var number: [String] = []
+var visited: [Bool] = []
+
+func solution(_ numbers: String) -> Int {
+
+    number = Array(numbers).map { String($0) }
+    visited = Array(repeating: false, count: number.count)
+    dfs("")
+
+    return result.count
+}
+
+func dfs(_ num: String) {
+    if let intNum = Int(num), isPrime(intNum) {
+        print(intNum)
+        result.insert(intNum)
+    }
+    for i in 0..<visited.count where !visited[i] {
+        visited[i] = true
+        dfs("\(num)\(number[i])")
+        visited[i] = false
+    }
+}
+
+func isPrime(_ num: Int) -> Bool {
+    if num == 1 || num == 0 { return false }
+    if num == 2 { return true }
+    for i in 2..<num where num.isMultiple(of: i) {
+        return false
+    }
+    return true
+}
+
+print(solution("011"))

2022/Sep/week_4/프로그래머스_Lv_입국심사_하늘이.swift

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+//
+//  main.swift
+//  Lv3_입국심사
+//
+//  Created by neuli on 2022/09/28.
+//
+
+import Foundation
+
+func solution(_ n: Int, _ times: [Int]) -> Int64 {
+
+    let times: [Int64] = times.sorted(by: <).map { Int64($0) }
+    var start: Int64 = 0
+    var end: Int64 = times.last! * Int64(n)
+
+    while start < end {
+        let mid = (start + end) / Int64(2)
+        var count: Int64 = 0
+        times.forEach {
+            count += mid / $0
+        }
+        if n <= count {
+            end = mid
+        } else {
+            start = mid + Int64(1)
+        }
+    }
+
+    return start
+}
+
+//  https://school.programmers.co.kr/questions/21374