💡 Intuition

• Idea is to track every number.
• If we track each number as we move forward in the array, we can check whether we've already seen that number in our tracking data structure.

🚀 Solution

func containsDuplicate(nums []int) bool {
    var set = map[int]int{};

    for _,value := range nums {
        if _, ok := set[value]; !ok  {
            set[value] = 1
        } else {
            return true;
        }
    }

    return false;
}

⏳ Time Complexity

• Since we are taking single loop for the array of length n, the time complexity will be O(n)