find_friends.py

def toDict(network):
    result = {}
    for c in network:
        left, right = c.split("-")
 
        if left in result:
            result[left].append(right)
        else:
            result[left] = [right]
 
        if right in result:
            result[right].append(left)
        else:
            result[right] = [left]
    return result
 
def check_connection(network, first, second):
    networkDict = toDict(network)    
    previousNodes = set(); previousNodes.add(first)
 
    for i in range(0, len(network)):
        currentNodes = set()
        for node in previousNodes:
            for adj in networkDict[node]:
                currentNodes.add(adj)
 
        if second in currentNodes:
            return True
 
        previousNodes = currentNodes
 
    return False