bzoj 1925 dp

#include<bits/stdc++.h>
#define LL long long
#define fi first
#define se second
#define mk make_pair
#define PII pair<int, int>
#define PLI pair<LL, int>
#define ull unsigned long long
using namespace std;

const int N = 4200 + 7;
const int inf = 0x3f3f3f3f;
const LL INF = 0x3f3f3f3f3f3f3f3f;
const int mod = 1e9 + 7;
const double eps = 1e-8;

int comb[2][N], cur;
int dp[N][2];
int n, p;

inline void add(int &a, int b) {
    a += b; if(a >= p) a -= p;
}

int main() {
    scanf("%d%d", &n, &p);
    dp[0][0] = dp[0][1] = 1;
    dp[1][0] = dp[1][1] = 1;
    dp[2][0] = dp[2][1] = 1;
    comb[0][0] = 1, comb[0][1] = 1;
    for(int i = 3; i <= n; i++) {
        cur ^= 1;
        for(int j = 0; j <= i-1; j++) {
            if(!j || j == i) comb[cur][j] = 1;
            else comb[cur][j] = (comb[cur^1][j-1]+comb[cur^1][j])%p;
        }
        for(int j = 2; j <= i; j += 2) {
            int pre = j - 1, suf = i - j;
            add(dp[i][0], 1ll*comb[cur][pre]*dp[pre][0]%p*dp[suf][0]%p);
        }
        for(int j = 1; j <= i; j += 2) {
            int pre = j - 1, suf = i - j;
            add(dp[i][1], 1ll*comb[cur][pre]*dp[pre][1]%p*dp[suf][0]%p);
        }
    }
    printf("%d\n", (dp[n][0]+dp[n][1])%p);
    return 0;
}

/*
*/