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 }