topological sort using kahns algorithm bfs + dfs

#method 1:using iterative approach bfs
class Solution:

    #Function to return list containing vertices in Topological order.
    def topoSort(self, V, adj):
        v=[False]*V
        q=[]
        def dfs(src):
            v[src]=True
            for node in adj[src]:
                if v[node]==False:
                    dfs(node)
            q.append(src)
        # Code here
        for i in range(V):
            if v[i]==False:
                dfs(i)
        return q[::-1]


#{
#  Driver Code Starts
# Driver Program


#method 2 dfs and colors method
'''
0--->unvisited
1--->processing
2--->processed
'''
class Solution:
    def findOrder(self,adj, n):

        def dfs(src):
            if vis[src]==1:return False
            vis[src]=1
            for ver in adj[src]:
                if vis[ver]!=2:#very imp
                    if dfs(ver)==False:
                        return False
            vis[src]=2
            ans.append(src)
        vis={i:0 for i in adj.keys()}
        for i in adj.keys():
            if vis[i]==0:
                if dfs(i)==False:return []
        return ans[::-1]
'''
These are not complete codes. Just edited some boiler plate but logic is correct.
Question link:
https://practice.geeksforgeeks.org/problems/alien-dictionary/1#
'''
#method 3 using dictionaruy
'''
Here also three colors but bit different
if key is not in vis:unvisited
if key is in vis and vis[key]==False:processed
if key is in vis and vis[key]==True:processing
'''

class Solution:
    def findOrder(self,adj, n):
        ans=[]

        def dfs(src):
            if src in vis:
                return vis[src]
            vis[src]=True
            for ver in adj[src]:
                if dfs(ver)==True:
                    return ''
            vis[src]=False
            ans.append(src)
        vis={}
        for i in adj.keys():
            if i not in vis:
                if dfs(i):return ''
        #print(ans[::-1])
        return ans[::-1]