24444_알고리즘 수업 - 너비 우선 탐색 1.swift

let input = readLine()!.split { $0 == " " }.map { Int($0)! }
let n = input[0], m = input[1], r = input[2]
var graph = [[Int]](repeating: [], count: n + 1)
var visited = [Int](repeating: 0, count: n + 1)

for _ in 0..<m {
    let input = readLine()!.split { $0 == " " }.map { Int($0)! }
    let a = input[0], b = input[1]
    graph[a].append(b)
    graph[b].append(a)
}

for i in 1...n { graph[i] = graph[i].sorted(by: <) }

var queue = [r]
var index = 0
var order = 1

visited[r] = 1
while queue.count > index {
    let currentNode = queue[index]
    for nextNode in graph[currentNode] {
        if visited[nextNode] == 0 {
            order += 1
            visited[nextNode] = order
            queue.append((nextNode))
        }
    }
    index += 1
}

print(visited[1...].map { String($0) }.joined(separator: "\n"))