【BZOJ-1324】Exca王者之剑 最小割

1324: Exca王者之剑

Time Limit: 10 Sec  Memory Limit: 162 MB
Submit: 483  Solved: 248
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Description

 

Input

第一行给出数字N,M代表行列数.N,M均小于等于100 下面N行M列用于描述数字矩阵

Output

输出最多可以拿到多少块宝石

Sample Input

2 2
1 2
2 1

Sample Output

4

HINT

Source

2007Amber国家队论文

Solution

最小割裸模型

见棋盘直接黑白染色，偶数秒发生消失？那就偶数秒和奇数秒分开二分图建图即可

Code

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
int read()
{
    int x=0,f=1; char ch=getchar();
    while (ch<'0' || ch>'9') {if (ch=='-') f=-1; ch=getchar();}
    while (ch>='0' && ch<='9') {x=x*10+ch-'0'; ch=getchar();}
    return x*f;
}
#define maxm 1000010
#define maxn 10010
int n,m,tot;
struct EdgeNode{int next,to,cap;}edge[maxm];
int head[maxn],cnt=1;
void add(int u,int v,int w)
{
    cnt++;
    edge[cnt].next=head[u]; head[u]=cnt; edge[cnt].cap=w; edge[cnt].to=v;
}
void insert(int u,int v,int w) {add(u,v,w); add(v,u,0);}

int val[110][110];

int dis[maxn],que[maxn<<1],cur[maxn],S,T;
bool bfs()
{
    for (int i=S; i<=T; i++) dis[i]=-1;
    que[0]=S; dis[S]=0; int he=0,ta=1;
    while (he<ta)
        {
            int now=que[he++];
            for (int i=head[now]; i; i=edge[i].next)
                if (edge[i].cap && dis[edge[i].to]==-1)
                    dis[edge[i].to]=dis[now]+1,que[ta++]=edge[i].to;
        }
    return dis[T]!=-1;
}
int dfs(int loc,int low)
{
    if (loc==T) return low;
    int w,used=0;
    for (int i=cur[loc]; i; i=edge[i].next)
        if (edge[i].cap && dis[edge[i].to]==dis[loc]+1)
            {
                w=dfs(edge[i].to,min(low-used,edge[i].cap));
                edge[i].cap-=w; edge[i^1].cap+=w;
                used+=w; if (edge[i].cap) cur[loc]=i;
                if (used==low) return low;
            }
    if (!used) dis[loc]=-1;
    return used;
}
#define inf 0x7fffffff
int dinic()
{
    int tmp=0;
    while (bfs())
        {
            for (int i=S; i<=T; i++) cur[i]=head[i];
            tmp+=dfs(S,inf);
        }
    return tmp;
}
int locate(int x,int y) {return (x-1)*m+y;}
int main()
{
    n=read(),m=read();
    for (int i=1; i<=n; i++)
        for (int j=1; j<=m; j++)
            val[i][j]=read(),tot+=val[i][j];
    S=0,T=n*m+1;
    for (int i=1; i<=n; i++)
        for (int j=1; j<=m; j++)
            if ((i+j)%2==1)
                {
                    insert(S,locate(i,j),val[i][j]);
                    if (i+1<=n) insert(locate(i,j),locate(i+1,j),inf);
                    if (i-1>=1) insert(locate(i,j),locate(i-1,j),inf);
                    if (j+1<=m) insert(locate(i,j),locate(i,j+1),inf);
                    if (j-1>=1) insert(locate(i,j),locate(i,j-1),inf);
                }
            else insert(locate(i,j),T,val[i][j]);
    int maxflow=dinic();
    printf("%d\n",tot-maxflow);
    return 0;
}

微机课随随便便打着玩系列，被旁边同学摁了个数，然后第一遍还WA了...纸张