int beautifulTriplets(int d, vector<int> arr) {
    
    unordered_set<int> s(arr.begin(), arr.end()); 
    int c = 0;

    for (size_t i = 0; i < arr.size(); i++) {
        if (s.count(arr[i]) && 
            s.count(arr[i] + d) && 
            s.count(arr[i] + 2 * d)) 
        {
            c++;
        }
    }
    return c;

}

    s = set(arr)
    c = 0
    for i in range(len(arr)-2):
        if arr[i] in s and arr[i]+d in s and arr[i]+(d*2) in s :
            c += 1
    return c

def beautifulTriplets(d, arr):
    # Write your code here
    c = 0 
    for i in range(len(arr)-2):
        x = [arr[i],arr[i]+d,arr[i]+(d*2)]
        y = [True if j in arr else False for j in x ]
        if all(y):
            c += 1
    return c

def beautifulTriplets(d, arr):
    # Write your code here
    
    count = 0
    lookup = set(arr)
    
    for i in arr:
        num2 = i + d
        num3 = num2 + d
        
        if num2 in lookup and num3 in lookup:
            count += 1
            
    return count