HDU 2686 Matrix(最大费用最大流+拆点)

题目链接：http://acm.hdu.edu.cn/showproblem.php?pid=2686

和POJ3422一样

删掉K把汇点与源点的容量改为2（因为有两个方向的选择）即可

#include 
#include 
#include 
#include 
#include 
#include 
const int maxn = 20000;
const int maxm = 800000;
const int inf = 1e8;
const int INF = 0x3f3f3f3f;
#define MIN INT_MIN
#define MAX 1e6
#define LL long long
#define init(a) memset(a,0,sizeof(a))
#define FOR(i,a,b) for(int i = a;ib)?(a):(b)
#define min(a,b) (a>b)?(b):(a)
using namespace std;
struct node
{
    int u,v,w,cap,next;
} edge[maxm];
int pre[maxn],dis[maxn],head[maxn],cnt;
bool vis[maxn];
int n;
void add(int u,int v,int c,int cap)
{
    edge[cnt].u=u;
    edge[cnt].v=v;
    edge[cnt].w=c;
    edge[cnt].cap=cap;
    edge[cnt].next=head[u];
    head[u]=cnt++;

    edge[cnt].u=v;
    edge[cnt].v=u;
    edge[cnt].w=-c;
    edge[cnt].cap=0;
    edge[cnt].next=head[v];
    head[v]=cnt++;
}
int spfa(int s,int t)
{
    queueq;
    while(q.empty()==false) q.pop();
    q.push(s);
    memset(vis,0,sizeof(vis));
    memset(pre,-1,sizeof(pre));
    FOR(i,s,t+1)
    dis[i] = -1;//求最长路dis数组初始化为-1

    dis[s]=0;
    vis[s] = 1;
    while(!q.empty())
    {
        int u=q.front();
        q.pop();
        vis[u] = 0;
        for(int i=head[u]; i!=-1; i=edge[i].next)
        {
            if(edge[i].cap && dis[edge[i].v] < (dis[u]+edge[i].w))//求最长路
            {
                dis[edge[i].v] = dis[u]+edge[i].w;
                pre[edge[i].v] = i;
                if(!vis[edge[i].v])
                {
                    vis[edge[i].v]=1;
                    q.push(edge[i].v);
                }
            }
        }

    }
    if(dis[t] != -1)//------------------忘改了。。
        return 1;
    else
        return 0;
}
int MinCostMaxFlow(int s,int t)
{
    int flow=0,cost=0;
    while(spfa(s,t))
    {
        int df = inf;
        for(int i = pre[t]; i!=-1; i=pre[edge[i].u])
        {
            if(edge[i].cap