【51nod】1565 模糊搜索

#include <iostream>
#include <algorithm>
#include <cstdio>
#include <cstring>
#include <vector>
#include <set>
#include <cmath>
#define enter putchar(‘\n‘)
#define space putchar(‘ ‘)
//#define ivorysi
#define pb push_back
#define MAXN 200005
#define pii pair<int,int>
#define mp make_pair
using namespace std;
typedef long long int64;
typedef double db;
template<class T>
void read(T &res) {
    res = 0;char c = getchar();T f = 1;
    while(c < ‘0‘ || c > ‘9‘) {
    if(c == ‘-‘) f = -1;
    c = getchar();
    }
    while(c >= ‘0‘ && c <= ‘9‘) {
    res = res * 10 - ‘0‘ + c;
    c = getchar();
    }
    res = res * f;
}
template<class T>
void out(T x) {
    if(x < 0) {x = -x;putchar(‘-‘);}
    if(x >= 10) out(x / 10);
    putchar(‘0‘ + x % 10);
}
const db PI = acos(-1.0);
char s1[MAXN],s2[MAXN];
int K,S,T;
int a[MAXN],b[MAXN],c[MAXN];
bool vis[MAXN];
struct Complex {
    db r,i;
    Complex(db real = 0.0,db image = 0.0) {
    r = real;i = image;
    }
    friend Complex operator + (const Complex &a,const Complex &b) {
    return Complex(a.r + b.r,a.i + b.i);
    }
    friend Complex operator - (const Complex &a,const Complex &b) {
    return Complex(a.r - b.r,a.i - b.i);
    }
    friend Complex operator * (const Complex &a,const Complex &b) {
    return Complex(a.r * b.r - a.i * b.i,a.r * b.i + a.i * b.r);
    }
}p1[MAXN * 4],p2[MAXN * 4];
void FFT(Complex *p,int L,int on) {
    for(int i = 1 , j = L / 2 ; i < L - 1 ; ++i) {
    if(i < j) swap(p[i],p[j]);
    int k = L / 2;
    while(j >= k) {
        j -= k;
        k >>= 1;
    }
    j += k;
    }
    for(int h = 2 ; h <= L ; h <<= 1) {
    Complex wn = Complex(cos(on * 2 * PI / h),sin(on * 2 * PI / h));
    for(int k = 0 ; k < L ; k += h) {
        Complex w = Complex(1.0,0.0);
        for(int j = k ; j < k + h / 2 ; ++j) {
        Complex u = p[j],t = p[j + h / 2] * w;
        p[j] = u + t;
        p[j + h / 2] = u - t;
        w = w * wn;
        }
    }
    }
    if(on == -1) {
    for(int i = 0 ; i < L ; ++i) p[i].r /= L;
    }
}
int ci(char c) {
    if(c == ‘A‘) return 1;
    else if(c == ‘G‘) return 2;
    else if(c == ‘C‘) return 3;
    else return 4;
}
void Init() {
    read(S);read(T);read(K);
    scanf("%s%s",s1 + 1,s2 + 1);
    for(int i = 1 ; i <= S ; ++i) a[i] = ci(s1[i]);
    for(int i = 1 ; i <= T ; ++i) b[i] = ci(s2[i]);
}
void Solve() {
    memset(vis,1,sizeof(vis));
    for(int i = 1 ; i <= 4;  ++i) {
    int t = 1;
    while(t <= S + T) t <<= 1;
    int cnt = 0;
    memset(c,0,sizeof(c));
    for(int j = 1 ; j <= S ; ++j) {
        if(a[j] == i) c[max(1,j - K)]++,c[min(j + K + 1,S + 1)]--;
    }
    for(int j = 1 ; j <= S ; ++j) {
        c[j] += c[j - 1];
        if(c[j]) p1[j - 1] = Complex(1.0,0.0);
        else p1[j - 1] = Complex(0.0,0.0);
    }
    for(int j = S ; j < t ; ++j) p1[j] = Complex(0.0,0.0);
    for(int j = 1 ; j <= T ; ++j) {
        if(b[j] == i) p2[T - j] = Complex(1.0,0.0),++cnt;
        else p2[T - j] = Complex(0.0,0.0);
    }
    for(int j = T ; j < t ; ++j) p2[j] = Complex(0.0,0.0);
    FFT(p1,t,1);FFT(p2,t,1);
    for(int j = 0 ; j < t ; ++j) p1[j] = p1[j] * p2[j];
    FFT(p1,t,-1);
    for(int j = 0 ; j < S ; ++j) {
        if((int)(p1[j].r + 0.5) == cnt) vis[j] &= 1;
        else vis[j] &= 0;
    }
    }
    int ans = 0;
    for(int i = 0 ; i < S ; ++i) if(vis[i]) ++ans;
    out(ans);enter;
}
int main() {
#ifdef ivorysi
    freopen("f1.in","r",stdin);
#endif
    Init();
    Solve();
}