题解 | #最长回文子串#

mystr=input()

n=len(mystr)
dp=[[0]*n for _ in range(n)]
for i in range(n):
    dp[i][i]=1
#如果一个字符串为回文，那么首尾去掉两个字母也是回文
max_len=0
for j in range(1,n):
    for i in range(n):
        if mystr[i]!=mystr[j]:
            dp[i][j]=0
        else:
            if j-i<3:
                dp[i][j]=1
            else:
                dp[i][j]=dp[i+1][j-1]
        if dp[i][j] and j-i+1>max_len:
            max_len=j-i+1
print(max_len)