mirror of
https://github.com/autistic-symposium/master-algorithms-py.git
synced 2025-04-30 12:46:11 -04:00
39 lines
979 B
Python
39 lines
979 B
Python
#!/bin/python
|
|
|
|
"""
|
|
Find a duplicate
|
|
We have a list of integers, where:
|
|
The integers are in the range 1..n1..n
|
|
The list has a length of n+1n+1
|
|
It follows that our list has at least one integer which appears at least twice. But it may have several duplicates, and each duplicate may appear more than twice.
|
|
|
|
Write a function which finds an integer that appears more than once in our list. (If there are multiple duplicates, you only need to find one of them.)
|
|
"""
|
|
|
|
def find_dups(num_list):
|
|
num_dict = {}
|
|
for n in num_list:
|
|
if n in num_dict.keys():
|
|
num_dict[n] += 1
|
|
else:
|
|
num_dict[n] = 1
|
|
|
|
for k,v in num_dict.items():
|
|
if v > 1:
|
|
print "dup is {}".format(k)
|
|
|
|
def find_dups_set(num_list):
|
|
|
|
num_set = set()
|
|
|
|
for n in num_list:
|
|
if n in num_set:
|
|
print n
|
|
else:
|
|
num_set.add(n)
|
|
|
|
|
|
num_list = [6,1,3,7,6,4,5,2,8,5,6,6,7]
|
|
find_dups(num_list)
|
|
find_dups_set(num_list)
|