计算Merkle Root

def solve(leaves):
    import hashlib
    leaves = leaves.split(',') if isinstance(leaves, str) else leaves
    def hash_pair(a, b):
        return hashlib.sha256((a + b).encode()).hexdigest()
    while len(leaves) > 1:
        if len(leaves) % 2 == 1:
            leaves.append(leaves[-1])
        leaves = [hash_pair(leaves[i], leaves[i+1]) for i in range(0, len(leaves), 2)]
    print(leaves[0])