Python真题案例之最长回文子串 周期串详解

# C语言风格实现
import sys
mystr=sys.stdin.readline().strip()
charr=""
charri=[]
mymax=-1
x=0
y=0
flag=True

j=-1
for i in mystr:
    j+=1
    if ord(i)<65 or ord(i)>122:
        continue
    else:
        charr+=i
        charri.append(j)
charr=charr.lower()

# print(charr,charri)
i=0
while i<len(charr):
    j=i
    while j<len(charr):
        k=i
        while k<=j:
            if charr[k]!=charr[i+j-k]:
                flag=False
                break
            k+=1
        if flag:
            if mymax<j-i+1:
                mymax=j-i+1
                x=i
                y=j
        flag=True
        j+=1
    i+=1 

print("第一种实现方式：")
print(x,y)
print(mystr[charri[x]:charri[y]+1:])

# python风格实现

import sys
mstr=sys.stdin.readline().strip()

tstr=""
snum=[]
smax=0
x=0
y=0
j=0
for i in mstr:
    if ord(i)>=65 and ord(i)<=122:
        tstr+=i
        snum.append(j)
    j+=1

tstr=tstr.lower()

for i in  range(len(tstr)):
    for j in range(i,len(tstr)+1):
        if tstr[i:j]==tstr[i:j][::-1] and len(tstr[i:j])>smax:
            smax=len(tstr[i:j])
            x=i
            y=j
print("第二种实现：")
print(x,y)
print(mstr[snum[x]:snum[y-1]+1])

import sys 
mmax=0
mystr=sys.stdin.readline().strip()
for i in range(1,len(mystr)):
    if len(mystr)%i==0:
        for j in range(0,len(mystr)//i-1):
            if mystr[j*i:j*i+i]!=mystr[(j+1)*i:(j+1)*i+i]:
                # print(mystr[j*i:j*i+i],"--",len(mystr[(j+1)*i:(j+1)*i+i]))
                break
        else:
            mmax=i
    if mmax!=0:
        break
    
print(mmax)