有序查找和二分查找

有序查找：

def linear_search(data_set,value):
    for i in range(len(data_set)):
        if data_set[i] == value:
            return i
    return

二分查找：

def bin_search(data_set,value):
    low=0
    high = len(data_set)-1
    while low <= high:
        mid = (low+high)//2
        if data_set[mid] == value:
            return mid
        elif data_set[mid] > value:
            high = mid-1
        else:
            low = mid+1


a = bin_search(range(1,40),24)
print(a)

注意：要求列表一定是有序的

例子：给定一个学生名单，包括姓名，年龄，id，按id从小到大有序排列，要求给出任意id值，查找对应的学生信息

import random

def random_list(n):
    result = []
    ids= list(range(1001,1001+n))
    a1 = ['赵','钱','孙','李']
    a2 = ['力','好']
    a3 = ['强','国']
    for i in range(n):
        age = random.randint(18,60)
        id = ids[i]
        name = random.choice(a1)+random.choice(a2)+random.choice(a3)
        dict = {
            'id':id,
            'name':name,
            'age':age,
        }
        result.append(dict)
    return result

def bin_search(data_set,value):
    low=0
    high = len(data_set)-1
    while low <= high:
        mid = (low+high)//2
        if data_set[mid]['id'] == value:
            return data_set[mid]
        elif data_set[mid]['id'] > value:
            high = mid-1
        else:
            low = mid+1

data_set = random_list(10000)
print(bin_search(data_set,7654))

两种算法的时间复杂度分别为O（n）和O（logn）