hdu 3068 (manacher算法)

hdu 3068 (manacher算法)

题目链接
参考大佬博客

#include <bits/stdc++.h>
using namespace std;
const int N = 110000 + 10;
char s[N*2];
int p[N*2];
int strlen1(char *s)
{
    int len = 0;
    for(int i=0;i<N-1;i++)
    {
        if(s[i]=='\0')
            return len;
        len++;
    }
}
int main()
{
    while(~scanf("%s",s))
    {
        int len = strlen1(s);
        for(int i=len;i>=0;i--)
        {
            s[i*2+2] = s[i];
            s[i*2+1] = '#';
        }
        s[0] = '*';
        int maxlen = 0,id = 0;
        for(int i=2;i<=len*2;i++)
        {
            if(p[id]+id>i)
                p[i] = min(p[id*2-i],p[id]+id-i);
            else
                p[i] = 1;
            while(s[i+p[i]]==s[i-p[i]])
                p[i]++;
            if(p[id]+id<p[i]+i)
                id = i;
            if(maxlen<p[i])
                maxlen = p[i];
        }
        printf("%d\n",maxlen-1);
    }
    return 0;
}