20250911 baekjoon

code_study/Baekjoon/swift/13549.swift

@@ -0,0 +1,64 @@
+struct Queue {
+    var enqueue: [Int] = []
+    var dequeue: [Int] = []
+    
+    func isEmpty() -> Bool {
+        return enqueue.isEmpty && dequeue.isEmpty
+    }
+    
+    mutating func push(_ element: Int) {
+        enqueue.append(element)
+    }
+    
+    mutating func pushFirst(_ element: Int) {
+        dequeue.append(element)
+    }
+    
+    mutating func pop() -> Int? {
+        if dequeue.isEmpty {
+            dequeue = enqueue.reversed()
+            enqueue.removeAll()
+        }
+        return dequeue.popLast()
+    }
+}
+
+if let NM = readLine()?.split(separator: " ").compactMap({Int($0)}),
+   let N = NM.first, let M = NM.last
+{
+    let maxAxis = 100000
+    var qu: Queue = Queue()
+    var visited: [Int] = Array(repeating: -1, count: maxAxis + 1)
+    qu.push(N)
+    visited[N] = 0
+    
+    while !qu.isEmpty() {
+        if let current: Int = qu.pop() {
+            if current == M {
+                print(visited[current])
+                break
+            }
+            
+            let nextAxis: [Int] = [current*2, current+1, current-1]
+            
+            for i in 0...2 {
+                let next: Int = nextAxis[i]
+                
+                if 0 <= next && next <= maxAxis {
+                    if i==0 {
+                        if visited[next] == -1 || visited[next] > visited[current] {
+                            qu.pushFirst(next)
+                            visited[next] = visited[current]
+                        }
+                    }
+                    else {
+                        if visited[next] == -1 || visited[next] > visited[current] + 1 {
+                            qu.push(next)
+                            visited[next] = visited[current] + 1
+                        }
+                    }
+                }
+            }
+        }
+    }
+}