Python | Join cycle in list
Sometimes, while dealing with graph problems in competitive programming, we have a list of pairs and we need to find if there is a possible cycle in it, and print all the elements in that cycle. Let’s discuss certain way in which this problem can be tackled.
Method : Using yield + loop + generator
The brute method to perform is to use a generator and keep printing the value if we know that the elements surely form a cycle and this is done by infinite loop and stopping when no more matches are found.
# Python3 code to demonstrate working of # Join cycle in list # Using yield + loop + generator # helper function to perform this task def cycle(test_list, val, stop = None): temp = dict(test_list) stop = stop if stop is not None else val while True: yield (val) val = temp.get(val, stop) if val == stop: break # initializing list test_list = [[6, 7], [9, 6], [7, 9]] # printing original list print("The original list is : " + str(test_list)) # Join cycle in list # Using yield + loop + generator # printing result print("The cycle elements are : ") for ele in cycle(test_list, 6): print(ele) |
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Output :
The original list is : [[6, 7], [9, 6], [7, 9]] The cycle elements are : 6 7 9
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