[bzoj2084] [Poi2010]Antisymmetry

 1 #include<cstdio>
 2 #include<iostream>
 3 #include<cstring>
 4 #include<algorithm>
 5 #define ll long long
 6 using namespace std;
 7 const int maxn=5e5+23;
 8 char s1[maxn];
 9 int s[maxn<<1],p[maxn<<1];
10 ll ans;
11 int i,j,k,n,m;
12  
13 int ra;char rx;
14 inline int read(){
15     rx=getchar(),ra=0;
16     while(rx<‘0‘||rx>‘9‘)rx=getchar();
17     while(rx>=‘0‘&&rx<=‘9‘)ra*=10,ra+=rx-48,rx=getchar();return ra;
18 }
19 int main(){
20     n=read();
21     scanf("%s",s1+1);
22     for(s[0]=‘%‘,s[1]=‘#‘,i=1;i<=n;i++)s[i<<1]=s1[i]-‘0‘,s[i<<1|1]=‘#‘;
23     n=n<<1|1;s[n+1]=‘^‘;
24     int mx=0,id=0;
25     for(i=1;i<=n;i++){
26         if(mx>i)p[i]=min(mx-i,p[id-(i-id)]);
27         while(s[i-p[i]]+s[i+p[i]]==1||s[i-p[i]]+s[i+p[i]]==‘#‘+‘#‘)p[i]++;
28         if(i+p[i]>mx)mx=i+p[i],id=i;
29         ans+=p[i]>>1;
30     }
31     printf("%lld\n",ans);
32 }
33