hud1569方格取数(2) （最大权独立集）

同1565一样，只是数据大了点。

/*****************************************
Author      :Crazy_AC(JamesQi)
Time        :2016
File Name   :
*****************************************/
// #pragma comment(linker, "/STACK:1024000000,1024000000")
#include <iostream>
#include <algorithm>
#include <iomanip>
#include <sstream>
#include <string>
#include <stack>
#include <queue>
#include <deque>
#include <vector>
#include <map>
#include <set>
#include <cstdio>
#include <cstring>
#include <cmath>
#include <cstdlib>
#include <climits>
using namespace std;
#define MEM(x,y) memset(x, y,sizeof x)
#define pk push_back
typedef long long LL;
typedef unsigned long long ULL;
typedef pair<int,int> ii;
typedef pair<ii,int> iii;
const double eps = 1e-10;
const int inf = 1 << 30;
const int INF = 0x3f3f3f3f;
const int MOD = 1e9 + 7;
int n, m;
const int maxn = 51*51;
int val[51][51];
int dx[] = {-1, 0, 1, 0};
int dy[] = {0, -1, 0, 1};
int s, t;
struct Edge{
    int from, to, cap, flow;
    Edge(){}
    Edge(int from,int to,int cap,int flow):from(from),to(to),cap(cap),flow(flow){}
};
struct ISAP{
    int p[maxn], num[maxn], cur[maxn], d[maxn];
    int s, t, n, m;
    bool vis[maxn];

    vector<int> G[maxn];
    vector<Edge> edges;

    void init(int n) {
        this->n = n;
        for (int i = 0;i <= n;++i) {
            G[i].clear();
            d[i] = INF;
        }
        edges.clear();
    }

    void addedge(int from,int to,int cap) {
        edges.push_back(Edge(from, to, cap, 0));
        edges.push_back(Edge(to, from, 0, 0));
        m = (int)edges.size();
        G[from].push_back(m - 2);
        G[to].push_back(m - 1);
    }

    bool bfs() {
        memset(vis, false,sizeof vis);

        queue<int> que;
        d[t] = 0;
        vis[t] = true;
        que.push(t);

        while(!que.empty()) {
            int u = que.front();
            que.pop();

            for (int i = 0;i < G[u].size();++i) {
                Edge& e = edges[G[u][i]^1];
                if (e.cap > e.flow && !vis[e.from]) {
                    vis[e.from] = true;
                    d[e.from] = d[u] + 1;
                    que.push(e.from);
                }
            }
        }
        return vis[s];
    }

    int Augment() {
        int u = t, flow = INF;
        while(u != s) {
            Edge& e = edges[p[u]];
            flow = min(flow, e.cap - e.flow);
            u = edges[p[u]].from;
        }

        u = t;
        while(u != s) {
            edges[p[u]].flow += flow;
            edges[p[u]^1].flow -= flow;
            u = edges[p[u]].from;
        }
        return flow;
    }

    int MaxFlow(int s,int t) {
        this->s = s,this->t = t;
        int ret = 0;
        bfs();
        if (d[s] >= n) return 0;

        memset(num, 0,sizeof num);
        memset(cur, 0,sizeof cur);
        for (int i = 0;i < n;++i) {
            if (d[i] < INF) num[d[i]]++;
        }
        int u = s;

        while(d[s] < n) {

            if (u == t) {
                ret += Augment();
                u = s;
            }

            bool ok = false;
            for (int i = cur[u];i < G[u].size();++i) {
                Edge& e = edges[G[u][i]];
                if (e.cap > e.flow && d[u] == d[e.to] + 1) {
                    ok = true;
                    p[e.to] = G[u][i];
                    cur[u] = i;
                    u = e.to;
                    break;
                }
            }

            if (!ok) {
                int Min = n - 1;
                for (int i = 0;i < G[u].size();++i) {
                    Edge& e = edges[G[u][i]];
                    if (e.cap > e.flow) Min = min(Min, d[e.to]);
                }
                if (--num[d[u]] == 0) break;
                num[d[u] = Min + 1]++;
                cur[u] = 0;
                if (u != s) u = edges[p[u]].from;
            }
        }
        return ret;
    }
}isap;
bool vis[51][51];
int main()
{ 
    // freopen("in.txt","r",stdin);
    // freopen("out.txt","w",stdout);
    while(~scanf("%d%d",&n,&m)) {
        // cout << "n = " << n << endl;
        // m = n;
        int sum = 0;
        // cout << "m = " << m << endl;
        for (int i = 1;i <= n;++i) 
            for (int j = 1;j <= m;++j) {
                scanf("%d",&val[i][j]);
                sum += val[i][j];
            }
        s = 0,t = n*m + 1;
        memset(vis, false,sizeof vis);
        isap.init(t);
        for (int i = 1;i <= n;++i) {
            for (int j = 1;j <= m;++j) {
                if (!vis[i][j]) {
                    int u = (i-1)*m+j;
                    isap.addedge(s, u, val[i][j]);
                    for (int k = 0;k < 4;++k) {
                        int nx = i + dx[k];
                        int ny = j + dy[k];
                        if (nx < 1 || nx > n || ny < 1 || ny > m) continue;
                        int v = (nx - 1)*m+ny;
                       if (!vis[nx][ny]) isap.addedge(v, t ,val[nx][ny]);
                        isap.addedge(u, v, INF);
                        vis[nx][ny] = true;
                        // val[nx][ny] = -3;
                    }
                }
            }
        }
        int ans = sum - isap.MaxFlow(s, t);
        printf("%d\n", ans);
    }
    return 0;
}