217. Contains Duplicate

Description:

Given an integer array nums, return true if any value appears at least twice in the array, and return false if every element is distinct.

'''
[1] sorting)

code::
def containsDuplicate(nums):
    nums.sort()
    
    for i in range(len(nums)-1):
        if nums[i]==nums[i+1]:
            return True
    return False

-T/C: O(nlogn)
-S/C: O(1)
'''

'''
[2] hashmap)

code::
def containsDuplicate(nums):
    counter={}
    
    for num in nums:
        if num in counter:
            return True
        else:
            counter[num]=1
    return False
    
-T/C: O(n) # one-pass
-S/C: O(n) # for dict()
'''

'''
[3] set)

code::
def containsDuplicate(self, nums):
    s=set()
    for num in nums:
        s.add(num)
    
    return len(s)!=len(nums)
    
-T/C: O(n) # one-pass
-S/C: O(n) # for set()
'''

class Solution:
    def containsDuplicate(self, nums: List[int]) -> bool:
        s=set()
        
        for num in nums:
            s.add(num)
            
        return len(s)!=len(nums)