方格取数--状压DP or 网络流

题意：http://acm.hdu.edu.cn/showproblem.php?pid=1565

取不相邻的点是权值最大。

这题可以网络流做，暂时先DP一下，网络流明天学一下~~

#define IOS ios_base::sync_with_stdio(0); cin.tie(0);
#include <cstdio>//sprintf islower isupper
#include <cstdlib>//malloc  exit strcat itoa system("cls")
#include <iostream>//pair
#include <fstream>//freopen("C:\Users\13606\Desktop\草稿.txt","r",stdin);
#include <bitset>
//#include <map>
//#include<unordered_map>
#include <vector>
#include <stack>
#include <set>
#include <string.h>//strstr substr
#include <string>
#include <time.h>// srand(((unsigned)time(NULL))); Seed n=rand()%10 - 0~9;
#include <cmath>
#include <deque>
#include <queue>//priority_queue<int, vector<int>, greater<int> > q;//less
#include <vector>//emplace_back
//#include <math.h>
//#include <windows.h>//reverse(a,a+len);// ~ ! ~ ! floor
#include <algorithm>//sort + unique : sz=unique(b+1,b+n+1)-(b+1);+nth_element(first, nth, last, compare)
using namespace std;//next_permutation(a+1,a+1+n);//prev_permutation
//******************
int abss(int a);
int lowbit(int n);
int Del_bit_1(int n);
int maxx(int a,int b);
int minn(int a,int b);
double fabss(double a);
void swapp(int &a,int &b);
clock_t __STRAT,__END;
double __TOTALTIME;
void _MS(){__STRAT=clock();}
void _ME(){__END=clock();__TOTALTIME=(double)(__END-__STRAT)/CLOCKS_PER_SEC;cout<<"Time: "<<__TOTALTIME<<" s"<<endl;}
//***********************
#define rint register int
#define fo(a,b,c) for(rint a=b;a<=c;++a)
#define fr(a,b,c) for(rint a=b;a>=c;--a)
#define mem(a,b) memset(a,b,sizeof(a))
#define pr printf
#define sc scanf
#define ls rt<<1
#define rs rt<<1|1
typedef long long ll;
const double E=2.718281828;
const double PI=acos(-1.0);
//const ll INF=(1LL<<60);
const int inf=(1<<30);
const double ESP=1e-9;
const int mod=(int)1e9+7;
const int N=(int)1e6+10;

int ok_num[N];
int dp[2][20000];
int a[25][25];

bool OK(int n,int x)
{
    int F[22];
    F[0]=0;
    for(int i=1;i<=n;++i)
        F[i]=(x>>(n-i))&1;
    for(int i=1;i<n;++i)
        if(F[i]&&F[i+1])return 0;
    return 1;
}
int get(int now,int state,int n)
{
    int F[22];
    F[0]=0;
    for(int i=1;i<=n;++i)
        F[i]=(state>>(n-i))&1;

    int temp=0;
    for(int i=1;i<=n;++i)
        if(F[i])temp+=a[now][i];
    return temp;
}

void solve(int n)
{
    int cnt=0;
    int tot=(1<<n)-1;
    for(int i=0;i<=tot;++i)
    {
        if(OK(n,i))
            ok_num[++cnt]=i;
    }
//    cout<<cnt<<endl;
    for(int i=1;i<=n;++i)
        for(int j=1;j<=n;++j)
            sc("%d",&a[i][j]);
    for(int i=0;i<=cnt;++i)
        dp[0][i]=dp[1][i]=0;
    for(int i=1;i<=n;++i)
    {
        for(int j=1;j<=cnt;++j)
        {
            int temp=get(i,ok_num[j],n);
        //    dp[1][j]=temp;
            for(int k=1;k<=cnt;++k)
            {
                if((ok_num[j]&ok_num[k])==0)
                    dp[1][j]=maxx(dp[1][j],temp+dp[0][k]);
            }
        }
        for(int j=1;j<=cnt;++j)
            dp[0][j]=dp[1][j],dp[1][j]=0;
    }
    int ans=0;
    for(int i=1;i<=cnt;++i)
        ans=maxx(ans,dp[0][i]);
    pr("%d
",ans);
}

int main()
{
    int n;
    while(~sc("%d",&n))solve(n);
    return 0;
}

/**************************************************************************************/

int maxx(int a,int b)
{
    return a>b?a:b;
}

void swapp(int &a,int &b)
{
    a^=b^=a^=b;
}

int lowbit(int n)
{
    return n&(-n);
}

int Del_bit_1(int n)
{
    return n&(n-1);
}

int abss(int a)
{
    return a>0?a:-a;
}

double fabss(double a)
{
    return a>0?a:-a;
}

int minn(int a,int b)
{
    return a<b?a:b;
}