[BaekJoon] 연산자 끼워넣기

Author: sustainable-git

BaekJoon/연산자 끼워넣기.swift

@@ -0,0 +1,46 @@
+import Foundation
+
+_ = readLine()!
+let numbers = readLine()!.split(separator: " ").map { Int(String($0))! }
+let operators = readLine()!.split(separator: " ").map { Int(String($0))! }
+
+guard operators.count == 4 && operators.reduce(0, +) + 1 == numbers.count else {
+    exit(-1)
+}
+
+func solution(numbers: [Int], operators: [Int]) -> (max: Int, min: Int) {
+    var result: [Int] = []
+    dfs(numbers: numbers, index: 1, leftOperators: operators, currentValue: numbers[0], result: &result)
+    result.sort()
+    
+    return (max: result.last!, min: result.first!)
+}
+
+func dfs(numbers: [Int], index: Int, leftOperators: [Int], currentValue: Int, result: inout [Int]) {
+    if index == numbers.count {
+        result.append(currentValue)
+        return
+    }
+    
+    for operatorIndex in 0..<leftOperators.count {
+        guard leftOperators[operatorIndex] > 0 else { continue }
+        var nextLeftOperators = leftOperators
+        nextLeftOperators[operatorIndex] -= 1
+        
+        switch operatorIndex {
+        case 0:
+            dfs(numbers: numbers, index: index + 1, leftOperators: nextLeftOperators, currentValue: currentValue + numbers[index], result: &result)
+        case 1:
+            dfs(numbers: numbers, index: index + 1, leftOperators: nextLeftOperators, currentValue: currentValue - numbers[index], result: &result)
+        case 2:
+            dfs(numbers: numbers, index: index + 1, leftOperators: nextLeftOperators, currentValue: currentValue * numbers[index], result: &result)
+        case 3:
+            dfs(numbers: numbers, index: index + 1, leftOperators: nextLeftOperators, currentValue: currentValue / numbers[index], result: &result)
+        default:
+            exit(-2)
+        }
+    }
+}
+
+let result = solution(numbers: numbers, operators: operators)
+print(result.max, result.min, separator: "\n")