Given an integer array nums, return true if any value appears at least twice in the array, and false if every element is distinct.
Important: Your solution must run in O(n) time. A brute-force O(n²) approach that compares every pair will be too slow.
Think about which data structure provides O(1) membership testing.
nums = [1, 2, 3, 1]truenums = [1, 2, 3, 4]falsenums = [1, 1, 1, 3, 3, 4, 3, 2, 4, 2]true1 <= nums.length <= 10^5-10^9 <= nums[i] <= 10^9Expected time complexity: O(n)Run your code to see results
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