洛谷.4897.[模板]最小割树(Dinic)

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我是靠谱客的博主疯狂嚓茶，这篇文章主要介绍洛谷.4897.[模板]最小割树(Dinic)，现在分享给大家，希望可以做个参考。

题目链接

最小割树模板。具体见：https://www.cnblogs.com/SovietPower/p/9734013.html。

ISAP不知为啥T成0分了。。

Dinic：

复制代码

//1566ms    2.24MB
#include <cstdio>
#include <cctype>
#include <cstring>
#include <algorithm>
//#define gc() getchar()
#define MAXIN 300000
#define gc() (SS==TT&&(TT=(SS=IN)+fread(IN,1,MAXIN,stdin),SS==TT)?EOF:*SS++)
typedef long long LL;
const int N=507,M=3007,INF=1e9;

int n,src,des,A[N],ans[N][N],Enum,H[N],fr[M],to[M],nxt[M],cap[M],Cap[M],pre[N],cur[N],lev[N];
bool vis[N];
char IN[MAXIN],*SS=IN,*TT=IN;

inline int read()
{
    int now=0;register char c=gc();
    for(;!isdigit(c);c=gc());
    for(;isdigit(c);now=now*10+c-'0',c=gc());
    return now;
}
void AE(int w,int v,int u)
{
    to[++Enum]=v, fr[Enum]=u, nxt[Enum]=H[u], H[u]=Enum, Cap[Enum]=w;
    to[++Enum]=u, fr[Enum]=v, nxt[Enum]=H[v], H[v]=Enum, Cap[Enum]=w;
}
bool BFS()
{
    static int q[N];
    int n=::n;
    memset(lev,0,n+2<<2);
    memcpy(cur,H,n+2<<2);
    int h=0,t=1; q[0]=src, lev[src]=1;
    while(h<t)
    {
        int x=q[h++];
        for(int i=H[x]; i; i=nxt[i])
            if(!lev[to[i]] && cap[i])
            {
                lev[to[i]]=lev[x]+1, q[t++]=to[i];
                if(to[i]==des) return 1;
            }
    }
    return 0;
}
int DFS(int x,int flow)
{
    if(x==des) return flow;
    int used=0;
    for(int &i=cur[x]; i; i=nxt[i])
        if(cap[i] && lev[to[i]]==lev[x]+1)
        {
            int delta=DFS(to[i],std::min(flow-used,cap[i]));
            if(delta)
            {
                cap[i]-=delta, cap[i^1]+=delta, used+=delta;
                if(used==flow) return flow;
            }
        }
    lev[x]=0;
    return used;
}
int Dinic()
{
    int res=0;
    while(BFS()) res+=DFS(src,INF);
    return res;
}
void Cut(int x)
{
    vis[x]=1;
    for(int i=H[x]; i; i=nxt[i])
        if(cap[i]&&!vis[to[i]]) Cut(to[i]);
}
void Solve(int l,int r)
{
    static int tmp[2][N];
    if(l==r) return;

for(int i=2; i<=Enum; ++i) cap[i]=Cap[i];
    src=A[l], des=A[r];
    int mincut=Dinic();

memset(vis,0,sizeof vis), Cut(src);
    for(int i=1; i<=n; ++i)
        if(vis[i])
            for(int j=1; j<=n; ++j)
                if(!vis[j]) ans[j][i]=ans[i][j]=std::min(ans[i][j],mincut);

int cnt[2]={0,0};
    for(int i=l,x=A[i]; i<=r; x=A[++i]) tmp[vis[x]][cnt[vis[x]]++]=x;
    for(int i=0; i<cnt[0]; ++i) A[l+i]=tmp[0][i];
    for(int i=0,mid=l+cnt[0]; i<cnt[1]; ++i) A[mid+i]=tmp[1][i];
    Solve(l,l+cnt[0]-1), Solve(l+cnt[0],r);
}

int main()
{
    Enum=1, n=read(); int m=read();
    for(int i=1; i<=m; ++i) AE(read(),read(),read());
    for(int i=1; i<=n; ++i) A[i]=i;
    memset(ans,0x3f,sizeof ans);
    Solve(1,n);
    for(int Q=read(); Q--; printf("%dn",ans[read()][read()]));

return 0;
}

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//1566ms    2.24MB
#include <cstdio>
#include <cctype>
#include <cstring>
#include <algorithm>
//#define gc() getchar()
#define MAXIN 300000
#define gc() (SS==TT&&(TT=(SS=IN)+fread(IN,1,MAXIN,stdin),SS==TT)?EOF:*SS++)
typedef long long LL;
const int N=507,M=3007,INF=1e9;

int n,src,des,A[N],ans[N][N],Enum,H[N],fr[M],to[M],nxt[M],cap[M],Cap[M],pre[N],cur[N],lev[N];
bool vis[N];
char IN[MAXIN],*SS=IN,*TT=IN;

inline int read()
{
    int now=0;register char c=gc();
    for(;!isdigit(c);c=gc());
    for(;isdigit(c);now=now*10+c-'0',c=gc());
    return now;
}
void AE(int w,int v,int u)
{
    to[++Enum]=v, fr[Enum]=u, nxt[Enum]=H[u], H[u]=Enum, Cap[Enum]=w;
    to[++Enum]=u, fr[Enum]=v, nxt[Enum]=H[v], H[v]=Enum, Cap[Enum]=w;
}
bool BFS()
{
    static int q[N];
    int n=::n;
    memset(lev,0,n+2<<2);
    memcpy(cur,H,n+2<<2);
    int h=0,t=1; q[0]=src, lev[src]=1;
    while(h<t)
    {
        int x=q[h++];
        for(int i=H[x]; i; i=nxt[i])
            if(!lev[to[i]] && cap[i])
            {
                lev[to[i]]=lev[x]+1, q[t++]=to[i];
                if(to[i]==des) return 1;
            }
    }
    return 0;
}
int DFS(int x,int flow)
{
    if(x==des) return flow;
    int used=0;
    for(int &i=cur[x]; i; i=nxt[i])
        if(cap[i] && lev[to[i]]==lev[x]+1)
        {
            int delta=DFS(to[i],std::min(flow-used,cap[i]));
            if(delta)
            {
                cap[i]-=delta, cap[i^1]+=delta, used+=delta;
                if(used==flow) return flow;
            }
        }
    lev[x]=0;
    return used;
}
int Dinic()
{
    int res=0;
    while(BFS()) res+=DFS(src,INF);
    return res;
}
void Cut(int x)
{
    vis[x]=1;
    for(int i=H[x]; i; i=nxt[i])
        if(cap[i]&&!vis[to[i]]) Cut(to[i]);
}
void Solve(int l,int r)
{
    static int tmp[2][N];
    if(l==r) return;

    for(int i=2; i<=Enum; ++i) cap[i]=Cap[i];
    src=A[l], des=A[r];
    int mincut=Dinic();

    memset(vis,0,sizeof vis), Cut(src);
    for(int i=1; i<=n; ++i)
        if(vis[i])
            for(int j=1; j<=n; ++j)
                if(!vis[j]) ans[j][i]=ans[i][j]=std::min(ans[i][j],mincut);

    int cnt[2]={0,0};
    for(int i=l,x=A[i]; i<=r; x=A[++i]) tmp[vis[x]][cnt[vis[x]]++]=x;
    for(int i=0; i<cnt[0]; ++i) A[l+i]=tmp[0][i];
    for(int i=0,mid=l+cnt[0]; i<cnt[1]; ++i) A[mid+i]=tmp[1][i];
    Solve(l,l+cnt[0]-1), Solve(l+cnt[0],r);
}

int main()
{
    Enum=1, n=read(); int m=read();
    for(int i=1; i<=m; ++i) AE(read(),read(),read());
    for(int i=1; i<=n; ++i) A[i]=i;
    memset(ans,0x3f,sizeof ans);
    Solve(1,n);
    for(int Q=read(); Q--; printf("%dn",ans[read()][read()]));

    return 0;
}

TLE的ISAP：

复制代码

#include <cstdio>
#include <cctype>
#include <cstring>
#include <algorithm>
#define gc() getchar()
typedef long long LL;
const int N=507,M=3007,INF=1e9;

int n,src,des,A[N],ans[N][N],Enum,H[N],fr[M],to[M],nxt[M],cap[M],Cap[M],pre[N],lev[N];
bool vis[N];

inline int read()
{
    int now=0;register char c=gc();
    for(;!isdigit(c);c=gc());
    for(;isdigit(c);now=now*10+c-'0',c=gc());
    return now;
}
void AE(int w,int v,int u)
{
    to[++Enum]=v, fr[Enum]=u, nxt[Enum]=H[u], H[u]=Enum, Cap[Enum]=w;
    to[++Enum]=u, fr[Enum]=v, nxt[Enum]=H[v], H[v]=Enum, Cap[Enum]=w;
}
bool BFS()
{
    static int q[N];
    int n=::n;
    for(int i=1; i<=n; ++i) lev[i]=n+1;
    int h=0,t=1; q[0]=des, lev[des]=0;
    while(h<t)
    {
        int x=q[h++];
        for(int i=H[x]; i; i=nxt[i])
            if(lev[to[i]]==n+1 && cap[i^1])
                lev[to[i]]=lev[x]+1, q[t++]=to[i];
    }
    return lev[src]<=n;
}
inline int Augment()
{
    int mn=INF;
    for(int i=des; i!=src; i=fr[pre[i]])
        mn=std::min(mn,cap[pre[i]]);
    for(int i=des; i!=src; i=fr[pre[i]])
        cap[pre[i]]-=mn, cap[pre[i]^1]+=mn;
    return mn;
}
int ISAP()
{
    static int cur[N],num[N];
    if(!BFS()) return 0;
    memset(num,0,n+2<<2);
    for(int i=1; i<=n; ++i) cur[i]=H[i],++num[lev[i]];
    int res=0,x=src;
    while(lev[src]<=n)
    {
        if(x==des) x=src,res+=Augment();
        bool can=0;
        for(int i=cur[x]; i; i=nxt[i])
            if(lev[to[i]]==lev[x]-1 && cap[i])
            {
                can=1, cur[x]=i, pre[x=to[i]]=i;
                break;
            }
        if(!can)
        {
            int mn=n;
            for(int i=H[x]; i; i=nxt[i])
                if(cap[i]) mn=std::min(mn,lev[to[i]]);
            if(!--num[lev[x]]) break;
            ++num[lev[x]=mn+1], cur[x]=H[x];
            if(x!=src) x=fr[pre[x]];
        }
    }
    return res;
}
void Cut(int x)
{
    vis[x]=1;
    for(int i=H[x]; i; i=nxt[i])
        if(cap[i]&&!vis[to[i]]) Cut(to[i]);
}
void Solve(int l,int r)
{
    static int tmp[2][N];
    if(l==r) return;

for(int i=2; i<=Enum; ++i) cap[i]=Cap[i];
    src=A[l], des=A[r];
    int mincut=ISAP();

memset(vis,0,sizeof vis), Cut(src);
    for(int i=1; i<=n; ++i)
        if(vis[i])
            for(int j=1; j<=n; ++j)
                if(!vis[j]) ans[j][i]=ans[i][j]=std::min(ans[i][j],mincut);

return 0;
}

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#include <cstdio>
#include <cctype>
#include <cstring>
#include <algorithm>
#define gc() getchar()
typedef long long LL;
const int N=507,M=3007,INF=1e9;

int n,src,des,A[N],ans[N][N],Enum,H[N],fr[M],to[M],nxt[M],cap[M],Cap[M],pre[N],lev[N];
bool vis[N];

inline int read()
{
    int now=0;register char c=gc();
    for(;!isdigit(c);c=gc());
    for(;isdigit(c);now=now*10+c-'0',c=gc());
    return now;
}
void AE(int w,int v,int u)
{
    to[++Enum]=v, fr[Enum]=u, nxt[Enum]=H[u], H[u]=Enum, Cap[Enum]=w;
    to[++Enum]=u, fr[Enum]=v, nxt[Enum]=H[v], H[v]=Enum, Cap[Enum]=w;
}
bool BFS()
{
    static int q[N];
    int n=::n;
    for(int i=1; i<=n; ++i) lev[i]=n+1;
    int h=0,t=1; q[0]=des, lev[des]=0;
    while(h<t)
    {
        int x=q[h++];
        for(int i=H[x]; i; i=nxt[i])
            if(lev[to[i]]==n+1 && cap[i^1])
                lev[to[i]]=lev[x]+1, q[t++]=to[i];
    }
    return lev[src]<=n;
}
inline int Augment()
{
    int mn=INF;
    for(int i=des; i!=src; i=fr[pre[i]])
        mn=std::min(mn,cap[pre[i]]);
    for(int i=des; i!=src; i=fr[pre[i]])
        cap[pre[i]]-=mn, cap[pre[i]^1]+=mn;
    return mn;
}
int ISAP()
{
    static int cur[N],num[N];
    if(!BFS()) return 0;
    memset(num,0,n+2<<2);
    for(int i=1; i<=n; ++i) cur[i]=H[i],++num[lev[i]];
    int res=0,x=src;
    while(lev[src]<=n)
    {
        if(x==des) x=src,res+=Augment();
        bool can=0;
        for(int i=cur[x]; i; i=nxt[i])
            if(lev[to[i]]==lev[x]-1 && cap[i])
            {
                can=1, cur[x]=i, pre[x=to[i]]=i;
                break;
            }
        if(!can)
        {
            int mn=n;
            for(int i=H[x]; i; i=nxt[i])
                if(cap[i]) mn=std::min(mn,lev[to[i]]);
            if(!--num[lev[x]]) break;
            ++num[lev[x]=mn+1], cur[x]=H[x];
            if(x!=src) x=fr[pre[x]];
        }
    }
    return res;
}
void Cut(int x)
{
    vis[x]=1;
    for(int i=H[x]; i; i=nxt[i])
        if(cap[i]&&!vis[to[i]]) Cut(to[i]);
}
void Solve(int l,int r)
{
    static int tmp[2][N];
    if(l==r) return;

    for(int i=2; i<=Enum; ++i) cap[i]=Cap[i];
    src=A[l], des=A[r];
    int mincut=ISAP();

    memset(vis,0,sizeof vis), Cut(src);
    for(int i=1; i<=n; ++i)
        if(vis[i])
            for(int j=1; j<=n; ++j)
                if(!vis[j]) ans[j][i]=ans[i][j]=std::min(ans[i][j],mincut);

    int cnt[2]={0,0};
    for(int i=l,x=A[i]; i<=r; x=A[++i]) tmp[vis[x]][cnt[vis[x]]++]=x;
    for(int i=0; i<cnt[0]; ++i) A[l+i]=tmp[0][i];
    for(int i=0,mid=l+cnt[0]; i<cnt[1]; ++i) A[mid+i]=tmp[1][i];
    Solve(l,l+cnt[0]-1), Solve(l+cnt[0],r);
}

int main()
{
    Enum=1, n=read(); int m=read();
    for(int i=1; i<=m; ++i) AE(read(),read(),read());
    for(int i=1; i<=n; ++i) A[i]=i;
    memset(ans,0x3f,sizeof ans);
    Solve(1,n);
    for(int Q=read(); Q--; printf("%dn",ans[read()][read()]));

    return 0;
}