【USACO 2006 November Gold】Corn Fields

【题目链接】

点击打开链接

【算法】

状压DP

【代码】

#include<bits/stdc++.h>
using namespace std;
#define MAXN 12
#define MOD 100000000

int M,N,i,j,k,ans,state;
int ST[MAXN+][(<<)+],f[MAXN+][(<<)+],cnt[MAXN+],mat[MAXN+][MAXN+];

template <typename T> inline void read(T &x) {
    int f = ; x = ;
    char c = getchar();
    for (; !isdigit(c); c = getchar()) { if (c == '-') f = -f; }
    for (; isdigit(c); c = getchar()) x = x *  + c - '';
    x *= f;
}
template <typename T> inline void write(T x) {
    if (x < ) { putchar('-'); x = -x; }
    if (x > ) write(x/);
    putchar(x%+'');
}
template <typename T> inline void writeln(T x) {
    write(x);
    puts("");
}

inline void dfs(int dep) {
    if (dep > N) ST[i][++cnt[i]] = state;
    else {
        dfs(dep+);
        if (mat[i][dep]) {
            if ((dep == ) || (!(state & ( << (N - dep + ))))) {
                state |= ( << (N - dep));
                dfs(dep+);
                state &= (~( << (N - dep)));
            }
        }
    }
}

int main() {

    read(M); read(N);

    for (i = ; i <= M; i++) {
        for (j = ; j <= N; j++) {
            read(mat[i][j]);
        }
    }    

    for (i = ; i <= M; i++) dfs();

    for (i = ; i <= cnt[]; i++) f[][i] = ;
    for (i = ; i <= M; i++) {
        for (j = ; j <= cnt[i]; j++) {
            for (k = ; k <= cnt[i-]; k++) {
                if (!(ST[i][j] & ST[i-][k]))
                    f[i][j] = (f[i][j] + f[i-][k]) % MOD;
            }
        }
    }

    for (i = ; i <= cnt[M]; i++) ans = (ans + f[M][i]) % MOD;
    writeln(ans);

    return ;

}