bzoj3790 神奇项链

#include<iostream>
#include<cstdio>
#include<cstring>
#include<cctype>
using namespace std;
template <typename T> inline T min(T &a,T &b) {return a<b ?a:b;}
template <typename T> inline T max(T &a,T &b) {return a>b ?a:b;}
char a[1000005],b[1000005];
int p[1000005],f[1000005];
int main(){
    while(scanf("%s",a)!=EOF){
        memset(f,0,sizeof(f));
        int len=strlen(a),n=0,id=0,mx=-1,last,mxd,ans=0;
        for(int i=0;i<len;++i) b[n++]=‘#‘,b[n++]=a[i];
        b[n++]=‘#‘;
        for(int i=0;i<n;++i){
            if(i<mx) p[i]=min(p[id*2-i],mx-i+1);
            else p[i]=1;
            while(i-p[i]>=0&&i+p[i]<n&&b[i-p[i]]==b[i+p[i]]) ++p[i];
            if(i+p[i]-1>mx) mx=i+p[i]-1,id=i;
            f[i-p[i]+1]=i+p[i]-1; //处理出从点i-p[i]+1开始的最长回文串长度
        }last=mxd=f[0]+2;
        for(int i=0;i<n;i+=2){ //贪心
            if(i==last) last=mxd,++ans;
            mxd=max(mxd,f[i]+2);
        }printf("%d\n",ans);
    }return 0;
}