217. Contains Duplicate

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.

Example 1:

Input: nums = [1,2,3,1]
Output: true

Example 2:

Input: nums = [1,2,3,4]
Output: false

Example 3:

Input: nums = [1,1,1,3,3,4,3,2,4,2]
Output: true

Constraints:

• 1 <= nums.length <= 10^5
• -10^9 <= nums[i] <= 10^9

Answer

func containsDuplicate(nums []int) bool {
    seen := make(map[int]bool)
    for _,num := range nums{
        if _,ok :=seen[num]; ok {
            return true
        }
        seen[num] = true
    }
    return false
}