计蒜客 2017 初赛第一场 B. 阿里天池的新任务（简单）

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KMP 板子题。

#include <bits/stdc++.h>
//#include <ext/pb_ds/tree_policy.hpp>
//#include <ext/pb_ds/assoc_container.hpp>
//using namespace __gnu_pbds;
using namespace std;

#define pi acos(-1)
#define endl '\n'
#define me(x) memset(x,0,sizeof(x));
#define foreach(it,a) for(__typeof((a).begin()) it=(a).begin();it!=(a).end();it++)
#define close() ios::sync_with_stdio(0);
#define rand() srand(time(0));
typedef long long LL;
typedef pair<int, int> pii;
const int INF=0x3f3f3f3f;
const LL LINF=0x3f3f3f3f3f3f3f3fLL;
const int dx[]={-1,0,1,0,-1,-1,1,1};
const int dy[]={0,1,0,-1,1,-1,1,-1};
const int maxn=1e3+5;
const int maxx=1e6+100;
const double EPS=1e-9;
const int MOD=1000000007;
#define mod(x) ((x)%MOD);
template<class T>inline T min(T a,T b,T c) { return min(min(a,b),c);}
template<class T>inline T max(T a,T b,T c) { return max(max(a,b),c);}
template<class T>inline T min(T a,T b,T c,T d) { return min(min(a,b),min(c,d));}
template<class T>inline T max(T a,T b,T c,T d) { return max(max(a,b),max(c,d));}
//typedef tree<pt,null_type,less< pt >,rb_tree_tag,tree_order_statistics_node_update> rbtree;
/*lch[root] = build(L1,p-1,L2+1,L2+cnt);
rch[root] = build(p+1,R1,L2+cnt+1,R2);中前*/
/*lch[root] = build(L1,p-1,L2,L2+cnt-1);
rch[root] = build(p+1,R1,L2+cnt,R2-1);中后*/
long long gcd(long long a , long long b){if(b==0) return a;a%=b;return gcd(b,a);}

int n,a,b,L,R,w[maxx],Next[maxx];
char s[maxx],t[maxx];
void init()
{
w[0]=b;
for(int i=1;i<n;i++)
w[i]=(w[i-1]+a)%n;
}
int ans=0;
void Getnext()
{
int i = 0,j = -1;
Next[i] = -1;
while(t[i] != '\0')
{
while(j != -1 && t[i] != t[j]) j = Next[j];
if(t[++i] != t[++j]) Next[i] = j;
else Next[i] = Next[j];
}
}
int KMP()
{
int i = 0,j = 0,ans = 0;
while(s[i] != '\0')
{
while(j != -1 && s[i] != t[j]) j = Next[j];
++i,++j;
if(j != -1 && t[j] == '\0') ++ans;
}
return ans;
}
int main()
{
cin>>n>>a>>b>>L>>R;
init();
for(int i=0;i<n;i++)
{
if(w[i]>=L&&w[i]<=R)
{
if((w[i]%2)==0)
{
s[i]='A';
}
else s[i]='T';
}
else
{
if(w[i]%2==0)
s[i]='G';
else s[i]='C';
}
}
cin>>t;
Getnext();
printf("%d\n",KMP());

}