217. Contains Duplicate

INFO

Problem: https://leetcode.com/problems/contains-duplicate/

Complexity: O(n)

class Solution {
    func containsDuplicate(_ nums: [Int]) -> Bool {
        var numCount: [Int: Int] = [:]
        for i in nums {
            if numCount[i] != nil {
                return true
            } else {
                numCount[i] = 1
            }
        }
        return false
    }
}

var solution = Solution()

var testcase1 = solution.containsDuplicate([1,2,3,1])
print(testcase1) // true

var testcase2 = solution.containsDuplicate([1,2,3,4])
print(testcase2) // false

var testcase3 = solution.containsDuplicate([1,1,1,3,3,4,3,2,4,2])
print(testcase3) // true