python二分法查找

比如要在列表arr中查找x

def f(arr, x):
    left = 0
    right = len(arr)
    while left < right:
        mid = (left + right) //2
        if mid < x:
            left = mid
        elif mid > x:
            right = mid
        else:
            return mid

arr = [ i for i in range(1,100)]
print(arr)
x = 69
y = f(arr, x)
print(y)

二分法查找postgresql数据库某个表的一条tuple

# -*- coding: utf-8 -*-
import psycopg2

conn = psycopg2.connect(host="192.168.137.129", port="1921", database="postgres", user="pg10", password="postgresql@123", )
conn.autocommit=True
cur = conn.cursor()

def get_ctids():
    cur.execute("SELECT ctid FROM test_toast order by ctid")
    rows = cur.fetchall()
    ctid_list = [eval(row[0]) for row in rows]
    cur.close()
    return ctid_list

def f(arr, x):
    left = 0
    right = len(arr)-1
    while left < right:
        mid = (left + right) // 2
        if arr[mid] < x:
            left = mid
        elif arr[mid] > x:
            right = mid
        else:
            return mid

def close_conn():
    conn.close()

if __name__ == '__main__':
    ctid_list = get_ctids()
    x = (1199,140)
    y = f(ctid_list, x)
    print(y, ctid_list[y])
    close_conn()