Manacher练习

看这篇博客学了下Manacher, 讲的很好, 但他的板子写错了..

https://www.cnblogs.com/Lyush/p/3221503.html

练习1 hdu 3068最长回文

板子题

#include <iostream>
#include <algorithm>
#include <cstdio>
#include <math.h>
#include <set>
#include <map>
#include <queue>
#include <string>
#include <string.h>
#define REP(i,a,n) for(int i=a;i<=n;++i)
#define PER(i,a,n) for(int i=n;i>=a;--i)
#define hr putchar(10)
#define pb push_back
#define lc (o<<1)
#define rc (lc|1)
#define mid ((l+r)>>1)
#define ls lc,l,mid
#define rs rc,mid+1,r
#define x first
#define y second
#define io std::ios::sync_with_stdio(false)
#define endl '\n'
using namespace std;

const int N = 1e6+10;
char s[N], S[N];
int n, rad[N];

int manacher(char *s) {
	for (int i=1,j=0,k; i<=n; i+=k) {
		while (s[i-j-1]==s[i+j+1]) ++j;
		rad[i] = j;
		for (k=1; k<=rad[i]&&rad[i-k]!=rad[i]-k; ++k) {
			rad[i+k] = min(rad[i-k], rad[i]-k);
		}
		j = max(j-k,0);
	}
	return *max_element(rad+1,rad+1+n);
}

void work() {
	n = strlen(s+1);
	S[1] = '#';
	REP(i,1,n) {
		S[i*2] = s[i];
		S[i*2+1] = '#';
	}
	n = 2*n+1, S[n+1] = '$';
	printf("%d\n", manacher(S));
}

int main() {
	for (; ~scanf("%s", s+1); ) work();
}