hdu 3068 Manacher算法

题意：求最长回文串，模板题

 1 #include<cstdio>
 2 #include<iostream>
 3 #include<algorithm>
 4 #include<cstring>
 5 #include<cmath>
 6 #include<queue>
 7 #include<map>
 8 using namespace std;
 9 #define MOD 1000000007
10 const int INF=0x3f3f3f3f;
11 const double eps=1e-5;
12 #define cl(a) memset(a,0,sizeof(a))
13 #define ts printf("*****\n");
14 int n,m,tt;const int MAXN=110010;
15 char Ma[MAXN*2];
16 int Mp[MAXN*2];
17 void Manacher(char s[],int len)
18 {
19     int l=0;
20     Ma[l++]=‘$‘;
21     Ma[l++]=‘#‘;
22     for(int i=0;i<len;i++)
23     {
24         Ma[l++]=s[i];
25         Ma[l++]=‘#‘;
26     }
27     Ma[l]=0;
28     int mx=0,id=0;
29     for(int i=0;i<l;i++)
30     {
31         Mp[i]=mx>i?min(Mp[2*id-i],mx-i):1;
32         while(Ma[i+Mp[i]]==Ma[i-Mp[i]])Mp[i]++;
33         if(i+Mp[i]>mx)
34         {
35             mx=i+Mp[i];
36             id=i;
37         }
38     }
39 }
40 char s[MAXN];
41 int main()
42 {
43     #ifndef ONLINE_JUDGE
44     freopen("1.in","r",stdin);
45     #endif
46     while(scanf("%s",s)==1)
47     {
48         int len=strlen(s);
49         Manacher(s,len);
50         int ans=0;
51         for(int i=0;i<2*len+2;i++)
52         ans=max(ans,Mp[i]-1);
53         printf("%d\n",ans);
54     }
55     return 0;
56 }