状态压缩

hiho1049 入门题

题目链接

#include <set>
#include <map>
#include <stack>
#include <queue>
#include <cmath>
#include <vector>
#include <string>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <iostream>
#include <algorithm>

#define MAX(a,b) ((a)>=(b)?(a):(b))
#define MIN(a,b) ((a)<=(b)?(a):(b))
#define OO 0x0fffffff
using namespace std;
typedef long long LL;
const int N = 1024;
const LL MOD = 1000000007;
LL dp[N][64];
int status[64],scnt;
int m,n;
bool judge(int data){
    bool want0 = false;
    for(int i=0;i<m;i++){
        if(!want0) want0 = !(data&1);
        else{
            if(data&1) return false;
            want0 = false;
        }
        data>>=1;
    }
    return (!want0);
}
int judge(int a,int b){
    int ret = 0;
    for(int i=0;i<m;i++){
        if((a&1)) {
            if(!(b&1)) return -1;
        }
        else if(b&1){
            ret += (1<<i);
        }
        a>>=1;
        b>>=1;
    }
    return ret;
}
int main(){
    cin>>n>>m;
    memset(dp,0,sizeof(dp));
    scnt = 0;
    for(int i=0;i<(1<<m);i++) {
        if(judge(i)) {
            dp[1][i] = 1;
            status[scnt++] = i;
        }
    }
    for(int i=1;i<n;i++) for(int j=0;j<(1<<m);j++){
        if(dp[i][j]){
            for(int s=0;s<scnt;s++){
                int news = judge(j,status[s]);
                if(news>=0) {
                    dp[i+1][news] += dp[i][j];
                    dp[i+1][news] %= MOD;
                }
            }
        }
    }
    printf("%lld
",dp[n][0]);
    return 0;
}