【Manacher】 HDOJ 3068 最长回文

Manacher学习资料请看http://acm.uestc.edu.cn/bbs/read.php?tid=4294

#include <iostream>  #include <queue>  #include <stack>  #include <map>  #include <set>  #include <bitset>  #include <cstdio>  #include <algorithm>  #include <cstring>  #include <climits>#include <cstdlib>#include <cmath>#include <time.h>#define maxn 300000#define maxm 300005#define eps 1e-10#define mod 1315423911#define INF 1e17#define lowbit(x) (x&(-x))#define mp make_pair#define ls o<<1#define rs o<<1 | 1#define lson o<<1, L, mid  #define rson o<<1 | 1, mid+1, R  typedef long long LL;typedef unsigned long long ULL;//typedef int LL;using namespace std;LL qpow(LL a, LL b){LL res=1,base=a;while(b){if(b%2)res=res*base;base=base*base;b/=2;}return res;}//LL powmod(LL a, LL b){LL res=1,base=a;while(b){if(b%2)res=res*base%mod;base=base*base%mod;b/=2;}return res;}void scanf(int &__x){__x=0;char __ch=getchar();while(__ch==' '||__ch=='\n')__ch=getchar();while(__ch>='0'&&__ch<='9')__x=__x*10+__ch-'0',__ch = getchar();}LL gcd(LL _a, LL _b){if(!_b) return _a;else return gcd(_b, _a%_b);}// headchar s[maxn], ss[maxn];int p[maxn], n;void kp(void){int id, mx = 0;for(int i = 1; i <= n; i++) {if(mx > i) p[i] = min(p[2 * id - i], mx - i);else p[i] = 1;for(; s[i+p[i]] == s[i-p[i]]; p[i]++);if(mx < i + p[i]) mx = i + p[i], id = i;}}void work(void){int len = strlen(ss), ans = 0;s[0] = '$', s[1] = '#';for(int i = 0; i < len; i++) s[(i+1)<<1] = ss[i], s[((i+1)<<1) + 1] = '#';n = len * 2 + 1, kp();s[n+1] = 0;for(int i = 1; i <= n; i++) ans = max(ans, p[i] - 1);printf("%d\n", ans);}int main(void){while(scanf("%s", ss)!=EOF) work();return 0;}