Leecode 217 Contains Duplicate ( C++,C#,Java,Javascript,Ruby)

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 <= 105 -109 <= nums[i] <= 109

//C++
class Solution {
public:
    bool containsDuplicate(vector<int>& nums) {
  
        unordered_set <int> hash ;
        
        for(int i = 0; i < nums.size(); i++)
        {
            if(hash.find(nums[i]) != hash.end())
                return true;
            else
                hash.insert(nums[i]);
        }
        return false;
    }
};
//C#
public class Solution {
    public bool ContainsDuplicate(int[] nums) {
        HashSet<int> hash = new HashSet<int>();
        
        for(int i = 0; i < nums.Length; i++)
        {
            if(hash.Contains(nums[i]))
                return true;
            else
                hash.Add(nums[i]);
        }
        return false;
    }
}
//Java
import java.util.*;
class ContainDuplicate{
    public static void main(String[] args) {
        Solution sl = new Solution();
        System.out.println(sl.containsDuplicate(new int[]{1,2,3,1}));
    }
}
class Solution {
    public boolean containsDuplicate(int[] nums) {
        HashSet<Integer> hash = new HashSet<Integer>();
        
        for(int i = 0; i < nums.length; i++)
        {
            if(hash.contains(nums[i]))
                return true;
            else
                hash.add(nums[i]);
        }
        return false;
    }
}
//Javascript
var containsDuplicate = function(nums) {
        
    let set = new Set();

    for(let i = 0; i < nums.length; i++)
    {
        if(set.has(nums[i]))
            return true;
        else
            set.add(nums[i]);
    }
    return false;
};

console.log(containsDuplicate([1,2,3,1]));
//Ruby
def contains_duplicate(nums)
    hash = {}
    
    nums.each do |x|
        if hash[x] == x
           return true 
        end    
        hash[x] = x;
    end
    
    false
end
#def contains_duplicate(nums)
#    nums != nums.uniq
#end
puts contains_duplicate([1,2,3,1]);