hdoj 3657 Game 【最小割 方格填数加强版】

2 2 1
2 2
2 2
1 1
2 2 1
2 7
4 1
1 1

4
9

HintAs to the second case in Sample Input, onmylove gan get the highest score when calulating like this:
2 + 7 + 4 － 2 × (2&4) － 2 × (2&7) = 13 － 2 × 0 － 2 × 2 = 9.

#include <cstdio>
#include <cstring>
#include <queue>
#include <algorithm>
#define MAXN 3000
#define MAXM 50000
#define INF 0x3f3f3f3f
using namespace std;
struct Edge
{
    int from, to, cap, flow, next;
};
Edge edge[MAXM];
int head[MAXN], edgenum;
int dist[MAXN], cur[MAXN];
bool vis[MAXN];
int N, M, k;
void init()
{
    edgenum = 0;
    memset(head, -1, sizeof(head));
}
int point(int x, int y)
{
    return (x-1) * M + y;
}
void addEdge(int u, int v, int w)
{
    Edge E1 = {u, v, w, 0, head[u]};
    edge[edgenum] = E1;
    head[u] = edgenum++;
    Edge E2 = {v, u, 0, 0, head[v]};
    edge[edgenum] = E2;
    head[v] = edgenum++;
}
int sum;//记录数值总和
int Map[60][60];
bool judge(int x, int y)
{
    return x >= 1 && x <= N && y >= 1 && y <= M && (x + y) % 2 == 0;
}
int source, sink;//超级源点 超级汇点
void getMap()
{
    int a, b;
    source = 0, sink = N*M+1;
    sum = 0;
    for(int i = 1; i <= N; i++)
    {
        for(int j = 1; j <= M; j++)
        {
            scanf("%d", &Map[i][j]);
            sum += Map[i][j];
            if((i + j) & 1)//奇数
                addEdge(source, point(i, j), Map[i][j]);
            else//偶数
                addEdge(point(i, j), sink, Map[i][j]);
        }
    }
    while(k--)
    {
        scanf("%d%d", &a, &b);
        if((a + b) & 1)
            addEdge(source, point(a, b), INF);//一定要选 该边不能被割掉
        else
            addEdge(point(a, b), sink, INF);
    }
    int move[4][2] = {0,1, 0,-1, 1,0, -1,0};
    for(int i = 1; i <= N; i++)
    {
        for(int j = 1; j <= M; j++)
        {
            if((i + j) & 1)
            {
                for(int k = 0; k < 4; k++)
                {
                    int x = i + move[k][0];
                    int y = j + move[k][1];
                    if(judge(x, y))//S集的点 向T集的点 建边
                        addEdge(point(i, j), point(x, y), 2*(Map[i][j] & Map[x][y]));
                }
            }
        }
    }
}
bool BFS(int s, int t)
{
    queue<int> Q;
    memset(dist, -1, sizeof(dist));
    memset(vis, false, sizeof(vis));
    dist[s] = 0;
    vis[s] = true;
    Q.push(s);
    while(!Q.empty())
    {
        int u = Q.front();
        Q.pop();
        for(int i = head[u]; i != -1; i = edge[i].next)
        {
            Edge E = edge[i];
            if(!vis[E.to] && E.cap > E.flow)
            {
                dist[E.to] = dist[u] + 1;
                if(E.to == t) return true;
                vis[E.to] = true;
                Q.push(E.to);
            }
        }
    }
    return false;
}
int DFS(int x, int a, int t)
{
    if(x == t || a == 0) return a;
    int flow = 0, f;
    for(int &i = cur[x]; i != -1; i = edge[i].next)
    {
        Edge &E = edge[i];
        if(dist[E.to] == dist[x] + 1 && (f = DFS(E.to, min(a, E.cap-E.flow), t)) > 0)
        {
            edge[i].flow += f;
            edge[i^1].flow -= f;
            flow += f;
            a -= f;
            if(a == 0) break;
        }
    }
    return flow;
}
int Maxflow(int s, int t)
{
    int flow = 0;
    while(BFS(s, t))
    {
        memcpy(cur, head, sizeof(head));
        flow += DFS(s, INF, t);
    }
    return flow;
}
int main()
{
    while(scanf("%d%d%d", &N, &M, &k) != EOF)
    {
        init();
        getMap();
        printf("%d\n", sum - Maxflow(source, sink));
    }
    return 0;
}