2017年上海金马五校程序设计竞赛：Find Palindrome

Description

Given a string S, which consists of lowercase characters, you need to find the longest palindromic sub-string.

A sub-string of a string S  is another string S'  that occurs "in" S. For example, "abst" is a sub-string of "abaabsta". A
palindrome is a sequence of characters which reads the same backward as forward.

 

Input

There are several test cases.

Each test case consists of one line with a single string S (1 ≤ |S | ≤ 50).

 

Output

For each test case, output the length of the longest palindromic sub-string.

 

Sample Input

sasadasa
bxabx
zhuyuan

 

Sample Output

7
1
3

#include <bits/stdc++.h>
using namespace std;
int xd(char a[],int w,int i,int j)
{
int u=0;
while(j>i)//j即倒数字符要一直大于i即正数字符
{
if(a[i]==a[j]&&a[i+1]==a[j-1])//如果相等并且下一对也相等，则数目加2；否则不匹配数目归零
{
u=u+2;
}
else
{
u=0;
}
i=i+1;
j=j-1;
}
if(i==j)//如果是回文串是奇数则数目加一，如果不是，则不加
{
u=u+1;
}
return u;
}
int main()
{
int n,i,j,q,w,u,v;
char a[51];
while(gets(a))
{
i=0;
u=0;
w=strlen(a);
j=w-1;
for(i=0;i<w;i++)//循环比较开始字符和倒数字符
for(j=w-1;j>=i;j--)
{
if(a[i]==a[j])//如果相等则进去函数
{
v=xd(a,w,i,j);
if(v>u)
u=v;
}
}
cout<<u<<endl;
}
return 0;
}