題目鏈接

最小割樹模板。具體見：https://www.cnblogs.com/SovietPower/p/9734013.html。

ISAP不知為啥T成0分了。。

Dinic：

//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("%d\n",ans[read()][read()]));return 0; }

TLE的ISAP：

#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("%d\n",ans[read()][read()]));return 0; }

轉載于:https://www.cnblogs.com/SovietPower/p/9811085.html

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