BZOJ3398: [Usaco2009 Feb]Bullcow 牡牛和牝牛(dp)

#include<cstdio>
#include<algorithm>
#include<stack>
#include<queue>
#include<cmath>
#define LL long long 
#define lb(x) (x & (-x))
#define Pair pair<int, int> 
#define fi first
#define se second
#define MP(x, y) make_pair(x, y)
using namespace std;
const int MAXN = 1e6 + 10, mod = 5000011;
inline int read() {
    char c = getchar(); int x = 0, f = 1;
    while(c < '0' || c > '9') {if(c == '-') f = -1; c = getchar();}
    while(c >= '0' && c <= '9') x = x * 10 + c - '0', c = getchar(); 
    return x * f;
}
int N, K;
int f[MAXN], g[MAXN];
int main() {
    N = read(); K = read();
    f[1] = 1; g[1] = 1;
    for(int i = 2; i <= N; i++) {
        f[i] = (f[i - 1] + g[i - 1]) % mod;
        g[i] = (f[max(i - K - 1, 1)] + g[max(i - K - 1, 0)]) % mod;
    }
    printf("%d", (f[N] + g[N]) % mod);
    return 0;
}
/*

*/