【算法】实现折半查找

二分（折半）查找实现，python版本

def zhebanchazhao( alist ,data):
    first = 0
    last = len(alist)-1
    mid=-1
    while first<=last:
        mid = (first + last) // 2
        print(mid)
        if alist[mid] == data:
            return mid,'找到了'
        elif alist[mid] < data:
            first = mid+1
        elif alist[mid] > data:
            last = mid-1
    return mid,'没找到'


if __name__== '__main__':
    test_list=[1,2,5,20,30,40,50]
    index,res=zhebanchazhao(test_list,5)
    print(index,res)