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  • uva10986 堆优化单源最短路径(pas)

    var n,m,s,t,v,i,a,b,c:longint;//这道题的代码不是这个,在下面
        first,tr,p,q:array[0..20000]of longint;
        next,eb,ew:array[1..100000]of longint;
    procedure swap(a,b:longint);
    var t:longint;
    begin
      t:=tr[a];tr[a]:=tr[b];tr[b]:=t;
      t:=p[a];p[a]:=p[b];p[b]:=t;
      t:=q[p[a]];q[p[a]]:=q[p[b]];q[p[b]]:=t;
    end;
    procedure sw(var a,b:longint);
    var t:longint;
    begin
      t:=a;a:=b;b:=t;
    end;
    procedure up(a:longint);
    begin
      if a=1 then exit;
      if tr[a]<tr[a div 2] then
      begin
        swap(a,a div 2);
        up(a div 2);
      end;
    end;
    procedure down(a:longint);
    var b,c:longint;
    begin
      b:=1;
      while(b<=a div 2)do
      begin
        c:=b*2;
        if(tr[c]>tr[c+1])and(c<n)then
          c:=c+1;
        if tr[c]<tr[b] then
          swap(b,c);
        b:=c;
      end;
    end;
    procedure input;
    begin
      v:=v+1;
      eb[v]:=b;
      ew[v]:=c;
      next[v]:=first[a];
      first[a]:=v;
    end;
    begin
      readln(n,m,s,t);
      v:=0;
      fillchar(first,sizeof(first),0);
      for i:=1 to m do
      begin
        readln(a,b,c);
        input;
        sw(a,b);
        input;
      end;
      fillchar(tr,sizeof(tr),$7f);
      tr[s+1]:=0;
      for i:=1 to n do
      begin
        p[i]:=i-1;
        q[i-1]:=i;
      end;
      up(s+1);
      write('Case #1: ');
      repeat
        a:=p[1]; //top
        if a=t then
        begin
          if tr[1]=2139062143 then
            writeln('unreachable')
          else
            writeln(tr[1]);
          break;
        end;
        b:=first[a];
        while(b<>0)do
        begin
          c:=eb[b];
          if(tr[q[a]]+ew[b]<tr[q[c]])then
          begin
            tr[q[c]]:=tr[q[a]]+ew[b];
            up(q[c]);
          end;
          b:=next[b];
        end;
        swap(1,n);
        n:=n-1;
        down(n);
      until false;
    end.

     单纯的堆优化dijkstra,

    加上多组数据以后(该题AC):

    var n,m,s,t,v,i,a,b,c,nn,ii:longint;
        first,tr,p,q:array[0..20000]of longint;
        next,eb,ew:array[1..100000]of longint;
    procedure swap(a,b:longint);
    var t:longint;
    begin
      t:=tr[a];tr[a]:=tr[b];tr[b]:=t;
      t:=p[a];p[a]:=p[b];p[b]:=t;
      t:=q[p[a]];q[p[a]]:=q[p[b]];q[p[b]]:=t;
    end;
    procedure sw(var a,b:longint);
    var t:longint;
    begin
      t:=a;a:=b;b:=t;
    end;
    procedure up(a:longint);
    begin
      if a=1 then exit;
      if tr[a]<tr[a div 2] then
      begin
        swap(a,a div 2);
        up(a div 2);
      end;
    end;
    procedure down(a:longint);
    var b,c:longint;
    begin
      b:=1;
      while(b<=a div 2)do
      begin
        c:=b*2;
        if(tr[c]>tr[c+1])and(c<n)then
          c:=c+1;
        if tr[c]<tr[b] then
          swap(b,c);
        b:=c;
      end;
    end;
    procedure input;
    begin
      v:=v+1;
      eb[v]:=b;
      ew[v]:=c;
      next[v]:=first[a];
      first[a]:=v;
    end;
    begin
    readln(nn);
    for ii:=1 to nn do
    begin
      readln(n,m,s,t);
      v:=0;
      fillchar(first,sizeof(first),0);
      for i:=1 to m do
      begin
        readln(a,b,c);
        input;
        sw(a,b);
        input;
      end;
      fillchar(tr,sizeof(tr),$7f);
      tr[s+1]:=0;
      for i:=1 to n do
      begin
        p[i]:=i-1;
        q[i-1]:=i;
      end;
      up(s+1);
      write('Case #',ii,': ');
      repeat
        a:=p[1]; //top
        if a=t then
        begin
          if tr[1]=2139062143 then
            writeln('unreachable')
          else
            writeln(tr[1]);
          break;
        end;
        b:=first[a];
        while(b<>0)do
        begin
          c:=eb[b];
          if(tr[q[a]]+ew[b]<tr[q[c]])then
          begin
            tr[q[c]]:=tr[q[a]]+ew[b];
            up(q[c]);
          end;
          b:=next[b];
        end;
        swap(1,n);
        n:=n-1;
        down(n);
      until false;
    end;
    end.
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  • 原文地址:https://www.cnblogs.com/wanglichao/p/4528822.html
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