【图论】【强连通分量】【Tarjan】pascal+邻接表

const    maxn = 100000;    maxm = 2*maxn;var    cost,toit,next:array[0..maxm] of longint;    list,dfn,low,stack:array[0..maxn] of longint;       n,m,top,i,j,d,tot,a,b,c:longint;    f,vis:array[0..maxn] of boolean;procedure add(a,b,c:longint);begin    inc(tot);    cost[tot]:=c;    toit[tot]:=b;    next[tot]:=list[a];    list[a]:=tot;end;function min(a,b:longint):longint;begin    if a<b then exit(a)    else exit(b);end;procedure print(x:integer);begin    while stack[tot]<>x do begin        writeln(stack[tot],' ');        f[stack[tot]]:=false;        dec(tot);    end;    writeln(stack[tot]);    f[stack[tot]]:=false;    dec(tot);end;procedure dfs(x:integer);var i,k,v:longint;begin    inc(d);    dfn[x]:=d;    low[x]:=d;    inc(tot);    stack[tot]:=x;    f[x]:=true;    k:=list[x];    while k<>0 do begin        v:=toit[k];        if not vis[v] then begin            vis[v]:=true;            dfs(v);            low[x]:=min(low[x],low[v]);        end        else if f[v] then low[x]:=min(low[x],dfn[v]);        k:=next[k];    end;    if dfn[x]=low[x] then print(x);end;begin    fillchar(list,sizeof(list),0);    fillchar(next,sizeof(next),0);    fillchar(toit,sizeof(toit),0);    fillchar(f,sizeof(f),false);    fillchar(vis,sizeof(vis),false);    readln(n,m);    tot:=0;    for i:=1 to m do begin        readln(a,b);        add(a,b);    end;        d:=0;tot:=0;    for i:=1 to n do if not vis[i] then begin        vis[i]:=true;        dfs(i);    end; end.