Solutions

# Use a set; or sort
# set
# Use set
def hasDuplicate(nums: list[int]) -> bool:
    seen = set()
    for num in nums:
        if num in seen:
            return True
        seen.add(num)
    return False

# Use set length
def hasDuplicate(nums: list[int]) -> bool:
    return len(nums) != len(set(nums))

# Sorting, O(nlogn) time, O(1) space
def hasDuplicate(nums: list[int]) -> bool:
    nums.sort()
    for i in range(1, len(nums)):
        if nums[i] == nums[i - 1]:
            return True
    return False

# Brute force, O(n^2) time, O(1) space
def hasDuplicate(nums: list[int]) -> bool:
    for i in range(len(nums)):
        for j in range(i + 1, len(nums)):
            if nums[i] == nums[j]:
                return True
    return False