hdu3068&&hdu3294，回文串，Manacher算法

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关于Manacher算法讲解在这
在o（n）时间内算出以每个点为中心的最大回文串长度

hdu3068
模板题

#include<cstdio>#include<string>#include<cstring>#include<iostream>#include<algorithm>using namespace std;const int N=233333;//20Wint Manacher(string st){    int len=st.size();    int *p=new int[len+1];    memset(p,0,sizeof(p));    int mx=0,id=0;    for (int i=1;i<=len;i++){        if (mx>i)p[i]=min(p[2*id-i],mx-i);        else p[i]=1;        while (st[i+p[i]]==st[i-p[i]])p[i]++;        if (i+p[i]>mx){mx=i+p[i];id=i;}    }    int ma=0;    for(int i=1;i<len;i++)ma=max(ma,p[i]);    delete(p);    return ma-1;}int main(){    //freopen("fuck.in","r",stdin);    char st[N];    while (~scanf("%s",st)){        string st0="$#";        for (int i=0;st[i]!='\0';i++){            st0+=st[i]; st0+="#";        }        printf("%d\n",Manacher(st0));    }    return 0;}

hdu3294
最后输出的时候稍微处理一下就好

#include<map>#include<cstdio>#include<string>#include<cstring>#include<iostream>#include<algorithm>using namespace std;const int N=200400;string ans;int _start,_end;int Manacher(string st){    int len=st.size();    int *p=new int[len+1];    memset(p,0,sizeof(p));    int mx=0,id=0;    for (int i=1;i<=len;i++){        if (mx>i)p[i]=min(p[id*2-i],mx-i);        else p[i]=1;        while (st[i+p[i]]==st[i-p[i]])p[i]++;        if (i+p[i]>mx)mx=i+p[i],id=i;    }    int ma=0,ii;    for (int i=1;i<len;i++)        if (p[i]>ma)ma=p[i],ii=i;    ma--;    _start=((ii-ma+1)>>1)-1;    _end  =((ii+ma-1)>>1)-1;    ans="";    for (int i=ii-ma;i<=ii+ma;i++)        if (st[i]!='#')ans+=st[i];    delete(p);    return ma;}void writeln(char ch,string st){    char tag='a'-1;    map<char,char>t;    for (char i=ch;i<='z';i++)t[i]=++tag;    for (char i='a';i< ch;i++)t[i]=++tag;    int len=st.size();    printf("%d %d\n",_start,_end);    for (int i=0;i<len;i++)printf("%c",t[st[i]]);    puts("");}int main(){    char ch,st[N];    while (~scanf("%c %s\n",&ch,st)){        string st0="$#";        for (int i=0;st[i]!='\0';i++)            {st0+=st[i];st0+="#";}        if (Manacher(st0)==1)puts("No solution!");        else writeln(ch,ans);    }    return 0;}

明天高数月考，，，，求rp++

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