[hdu 3376]Matrix Again

这题就是真正的费用流了，用 大屁 就算不超时，你也有个 CE :数组 so large

拆点，费用取反，最大费用最大流即可了喵~

不过似乎这题很不兼容 dijkstra 的样子

就算用 spfa 重赋权把边权搞正后依然 TLE ，额不是说 dijstra 正权图最强么？

一定是我没有手写堆，一定是的……

 

#include <cstdio>
#include <cstring>
#include <queue>
#define min(x, y) ((x)<(y) ? (x):(y))
const int inf=0x7F7F7F7F;
const int sizeOfPoint=800008;
const int sizeOfEdge=8000008;

int n;
int V;
int S, T;
int a[666][666][2];
bool vis[sizeOfPoint];
int h[sizeOfPoint];
inline int getint();
inline void putint(int);

struct edge {int point, flow, cost; edge * next, * pair;};
edge memory[sizeOfEdge], * port=memory;
edge * e[sizeOfPoint];
inline void clear() {port=memory; memset(e, 0, sizeof e); memset(a, 0, sizeof a);}
inline edge * newedge(int point, int flow, int cost, edge * next)
{
    edge * ret=port++;
    ret->point=point; ret->flow=flow; ret->cost=cost; ret->next=next;
    return ret;
}
inline void link(int u, int v, int f, int c)
{
    e[u]=newedge(v, f, c, e[u]); e[v]=newedge(u, 0, -c, e[v]);
    e[u]->pair=e[v]; e[v]->pair=e[u];
}
inline bool spfa();
int aug(int, int);
inline int costflow();

int main()
{
    while (scanf("%d", &n)!=EOF)
    {
        clear();
        V=0;
        for (int i=1;i<=n;i++)
            for (int j=1;j<=n;j++)
            {
                a[i][j][0]=++V; a[i][j][1]=++V;
                link(a[i][j][0], a[i][j][1], 1, -getint());
            }

        link(a[1][1][0], a[1][1][1], 1, 0);
        link(a[n][n][0], a[n][n][1], 1, 0);
        S=1; T=V;
        for (int i=1;i<=n;i++)
            for (int j=1;j<=n;j++)
            {
                if (i<n) link(a[i][j][1], a[i+1][j][0], 1, 0);
                if (j<n) link(a[i][j][1], a[i][j+1][0], 1, 0);
            }
        putint(-costflow());
    }

    return 0;
}

inline int getint()
{
    register int num=0;
    register char ch;
    do ch=getchar(); while (ch<'0' || ch>'9');
    do num=num*10+ch-'0', ch=getchar(); while (ch>='0' && ch<='9');
    return num;
}
inline void putint(int num)
{
    char stack[15];
    register int top=0;
    for ( ;num;num/=10) stack[++top]=num%10+'0';
    for ( ;top;top--) putchar(stack[top]);
    putchar('\n');
}

inline bool spfa()
{
    static std::queue<int> q;
    static bool inque[sizeOfPoint];
    memset(h, 0x7F, sizeof h); h[T]=0;
    memset(inque, 0, sizeof inque);
    for (inque[T]=true, q.push(T);q.size();q.pop())
    {
        int u=q.front();
        inque[u]=false;
        for (edge * i=e[u];i;i=i->next) if (i->pair->flow && h[i->point]>h[u]+i->pair->cost)
        {
            h[i->point]=h[u]+i->pair->cost;
            q.push(i->point);
            if (!inque[i->point]) inque[i->point]=true, q.push(i->point);
        }
    }
    return h[S]<inf;
}
int aug(int u, int flow)
{
    int left=flow;
    if (u==T) return flow;
    vis[u]=true;
    for (edge * i=e[u];i;i=i->next) if (!vis[i->point] && i->flow && h[u]==h[i->point]+i->cost)
    {
        int temp=aug(i->point, min(left, i->flow));
        i->flow-=temp; i->pair->flow+=temp; left-=temp;
        if (!left) break;
    }
    vis[u]=false;
    return flow-left;
}
inline int costflow()
{
    int ret=0;
    while (spfa())
        ret+=h[S]*aug(S, inf);
    return ret;
}