785. Is Graph Bipartite?

leetcode785.swift

class Solution {
    func isBipartite(_ graph: [[Int]]) -> Bool {
        var group = [Int:Bool]()        
        for (index, node) in graph.enumerated() {
            guard group[index] == nil else {
                continue
            }
            
            var queue = [index]
            var currentGroup = true
            while !queue.isEmpty {

                var nextQueue = [Int]()

                for node in queue {
                    if let nodeGroup = group[node] {
                        if nodeGroup != currentGroup {
                            return false
                        } else {
                            continue
                        }
                    } else {
                        group[node] = currentGroup
                        nextQueue.append(contentsOf: graph[node])
                    }

                }

                currentGroup.toggle()

                queue = nextQueue
            }
        }
        return true
    }
}