POJ 1459 ZOJ 1734 Power Network dinic 算法 网络流

裸的网络流，就是在读数据的时候，注意用while(getchar()!='(');scanf("%d,%d),%d");

然后增加超源点与超收点。我是用dinic算法，速度慢，跑了549貌似ms，貌似，希望能优化，用个什么预流推进算法试试啊。

在纠结了很久后，终于在书上把预流推进算法抄下来了，哈哈，调试了很久，一直陷入死循环，后来一看输入文件不是这个题的输入，想shi啊，有木有

贴代码  dinic 算法 ：

#include <cstdio>
#include <cstring>
#define MAXN 108
#define INF 300000000
int n,np,nc,m;
int s ;//源点
int t; //汇点
int map[MAXN][MAXN];//容量网络
bool sign[MAXN][MAXN];//层次网络
void init()
{
    int i;
    int u,v,z;
    s = n;
    t = n+1;
    memset(map,0,sizeof(map));
    for(i=0; i<m; ++i)
    {
        while(getchar() != '(');
        scanf("%d,%d)%d",&u,&v,&z);
        map[u][v] = z;
    }
    for(i=0; i<np; ++i)
    {
        while(getchar() != '(');
        scanf("%d)%d",&u,&z);
        map[s][u] = z;
    }
    for(i =0; i<nc; ++i)
    {
        while(getchar() != '(');
        scanf("%d)%d",&u,&z);
        map[u][t] = z;
    }
}
int min(int x,int y)
{
    return x<y ? x : y;
}
bool BFS()
{
    bool used[MAXN];
    int queue[MAXN];
    int fr=0,ta=0;
    int i;
    memset(used,0,sizeof(used));
    memset(sign,0,sizeof(sign));
    queue[ta++] = s;
    used[s] = 1;
    while(fr != ta)
    {
        int v = queue[fr++];
        for(i=0; i<=n+1; ++i)
        {
            if(!used[i] && map[v][i])
            {
                queue[ta++] = i;
                sign[v][i] = 1;
                used[i] = 1;
            }
        }
    }
    return used[t];
}
int  DFS(int v,int sum)
{
    int i,r,f;
    if(v == t) return sum;
    r = sum;
    for(i=0; i<=n+1; ++i)
    {
        if(sign[v][i])
        {
            f=DFS(i,min(map[v][i],sum));
            map[v][i] -=f;
            map[i][v] += f;
            sum -= f;
        }
    }
    return r-sum;
}
int main()
{
//    freopen("in.cpp","r",stdin);
    while(~scanf("%d%d%d%d",&n,&np,&nc,&m))
    {
        init();
        int ans = 0;
        while(BFS()) ans += DFS(s,INF);
        printf("%d\n",ans);
    }
    return 0;
}

预流推进算法，只跑了150ms,貌似：

#include <cstdio>
#include <cstring>
#include <queue>
#define MAXN 110
#define INF 0x7fffffff  //相当于21，4748，3647
using namespace std;
int s,t; //源点和汇点
queue<int> act;
int h[MAXN];  //高度
int ef[MAXN]; //余流，能流出去多少
int n,np,nc,m;
int resi[MAXN][MAXN];//残留网络，每条边的权值表示容量
int min(int x,int y)
{
    if(x <y)return x;
    else return y;
}
void pushRelabel()
{
    int i;
    int sum=0;
    int u,p;
    memset(ef,0,sizeof(ef));
    memset(h,0,sizeof(h));
    h[s] = n+2;
    ef[s] = INF;//源点能往外流正无穷
    ef[t] = -INF;//汇点不能往外流，所以汇点能往外流负无穷
    act.push(s);
    while(!act.empty())
    {
        u = act.front();
        act.pop();
        for(i=0; i<=n+1; ++i)
        {
            p = min(resi[u][i],ef[u]);
            if(p > 0 && (u==s || h[u] == h[i]+1))
            {
                resi[u][i] -= p;
                resi[i][u] += p;
                ef[u] -= p;
                ef[i] += p;
                if(i == t) sum += p;
                if(i != s && i!=t)
                    act.push(i);
            }
        }
        if(u != s && u != t && ef[u] > 0)
        {
            h[u]++;
            act.push(u);
        }
    }
    printf("%d\n",sum);
}
int main()
{
//    freopen("in.cpp","r",stdin);
    int i;
    int u,v,val;
    while(~scanf("%d%d%d%d",&n,&np,&nc,&m))
    {
        s = n;
        t = n+1;
        memset(resi,0,sizeof(resi));
        for(i=0; i<m; ++i)
        {
            while(getchar()!='(');
            scanf("%d,%d)%d",&u,&v,&val);
            resi[u][v] = val;
        }
        for(i=0; i<np; ++i)
        {
            while(getchar()!='(');
            scanf("%d)%d",&u,&val);
            resi[s][u] = val;
        }
        for(i=0; i<nc; ++i)
        {
            while(getchar()!='(');
            scanf("%d)%d",&u,&val);
            resi[u][t] = val;
        }
        pushRelabel();
    }
    return 0;
}