Thay thế từng phần tử theo thứ hạng

def replace_with_rank(arr):
    # Optimized: Use sorting and a dictionary
    if not arr: return []
    
    # Get unique elements sorted
    sorted_unique = sorted(list(set(arr)))
    
    # Map each element to its rank
    rank_map = {val: i + 1 for i, val in enumerate(sorted_unique)}
    
    # Replace elements with ranks
    return [rank_map[x] for x in arr]

def replace_with_rank(arr):
    # Brute force: For each element, count how many smaller unique elements exist
    n = len(arr)
    ranks = []
    for i in range(n):
        smaller_unique = set()
        for j in range(n):
            if arr[j] < arr[i]:
                smaller_unique.add(arr[j])
        ranks.append(len(smaller_unique) + 1)
    return ranks