[DFS] 백준 2644번: 촌수계산(Swift)

난이도: 실버 2

사용 언어: Swift

카테고리: DFS

https://www.acmicpc.net/problem/2644

2644번: 촌수계산

Code

let n = Int(readLine()!)!
let sf = readLine()!.split(separator: " ").map { Int($0)! }
let start = sf[0]
let finish = sf[1]
let m = Int(readLine()!)!

var visited = Array(repeating: false, count: n + 1)
var links: [[Int]] = Array(repeating: [], count: n + 1)

for _ in 0..<m {
  let v = readLine()!.split(separator: " ").map { Int($0)! }
  links[v[0]].append(v[1])
  links[v[1]].append(v[0])
}

var result = 0
var isSuccess = false

func dfs(start: Int, count: Int) {
  visited[start] = true
  if start == finish {
    result = count
    isSuccess = true
    return
  }
  
  for i in links[start] {
    if !visited[i] {
      dfs(start: i, count: count + 1)
    }
  }
}

dfs(start: start, count: 0)
result = isSuccess ? result : -1
print(result)