用 ZSCORE 或 ZRANK 命令模拟 ZEXISTS 命令

gistfile1.py

from redis import Redis

r = Redis()

# T = O(1)
def zexists_1(key, member):
    return r.zscore(key, member) is not None

# T = O(log N)
def zexists_2(key, member):
    return r.zrank(key, member) is not None