def sequefind(l,x):
    k=0
    while k<=len(l)-1 and x!=l[k]:
        k=k+1
    if k>len(l)-1:
        return 0
    else:
        return k

s=[1,4,5,6,7]
while(1):
    key=int(input(“input your want number”))
    n=sequefind(s,key)
    if n==0:
        print(“not found!”)
    else:
        print(key,”IS”,n+1,”element”)

顺序查找改进版函数：

def improveseque(l,x):
    l[0]=x
    k=len(l)-1
    while x!=l[k]:
        k=k-1
    return k

#用for的方式写出来

def simseq(l,s):
    i=0
    for value in l:
        if value==s:
            return i
        i+=1
    else:
        return -1
l=[1,4,5,6,7]
key=int(input(“input your want number”))
n=simseq(l,key)
if n==-1:
    print(“not found!”)
else:
    print(key,”IS”,n+1,”element”)

#哨兵查找

def reserch(l,v):
    l.append(v)
    i=0
    while l[i]!=v:
        i=i+1
    else:
        l.pop()
    return i
l=[1,4,5,6,7]
key=int(input(“input your want number”))
n=reserch(l,key)
if n>len(l)-1:
    print(“not found!”)
else:
    print(key,”IS”,n+1,”element”)