dfs.go

func IsNonCyclic(edges [][]int) bool {
    adjList := make(map[int][]int)
    for _, edge := range edges{
        node1, node2 := edge[0], edge[1]
_, ok := adjList[node1]
        if !ok{
            adjList[node1] = []int{node2}
        }else{
            adjList[node1] = append(adjList[node1], node2)
        }
    } 
    visited := make(map[int]int)
    for node:= range adjList{
        if visited[node] == 1{
            continue
        }
        if !dfs(node, adjList, &visited){
            return false
        }
    }
    return true
}
func dfs(node int, adjList map[int][]int, visited *map[int]int) bool { 
    neighbourArr, ok := adjList[node]
    if !ok{
        return true
    }
    
    if (*visited)[node] == -1{
        return false
    }
    
    if (*visited)[node] == 1{
        return true
    }
    
    (*visited)[node] = -1
    
    for _, neighbour := range neighbourArr{
        if !dfs(neighbour, adjList, visited){
            return false
        }
    }
    (*visited)[node] = 1
    return true
}