NOI2014 魔法森林

3669: [Noi2014]魔法森林

Time Limit: 30 Sec  Memory Limit: 512 MB
Submit: 106  Solved: 62
[Submit][Status]

Description

为了得到书法大家的真传，小E同学下定决心去拜访住在魔法森林中的隐士。魔法森林可以被看成一个包含个N节点M条边的无向图，节点标号为1..N，边标号为1..M。初始时小E同学在号节点1，隐士则住在号节点N。小E需要通过这一片魔法森林，才能够拜访到隐士。

魔法森林中居住了一些妖怪。每当有人经过一条边的时候，这条边上的妖怪就会对其发起攻击。幸运的是，在号节点住着两种守护精灵：A型守护精灵与B型守护精灵。小E可以借助它们的力量，达到自己的目的。

只要小E带上足够多的守护精灵，妖怪们就不会发起攻击了。具体来说，无向图中的每一条边Ei包含两个权值Ai与Bi。若身上携带的A型守护精灵个数不少于Ai，且B型守护精灵个数不少于Bi，这条边上的妖怪就不会对通过这条边的人发起攻击。当且仅当通过这片魔法森林的过程中没有任意一条边的妖怪向小E发起攻击，他才能成功找到隐士。

由于携带守护精灵是一件非常麻烦的事，小E想要知道，要能够成功拜访到隐士，最少需要携带守护精灵的总个数。守护精灵的总个数为A型守护精灵的个数与B型守护精灵的个数之和。

Input

第1行包含两个整数N,M，表示无向图共有N个节点，M条边。 接下来M行，第行包含4个正整数Xi,Yi,Ai,Bi，描述第i条无向边。其中Xi与Yi为该边两个端点的标号，Ai与Bi的含义如题所述。 注意数据中可能包含重边与自环。

Output

输出一行一个整数：如果小E可以成功拜访到隐士，输出小E最少需要携带的守护精灵的总个数；如果无论如何小E都无法拜访到隐士，输出“-1”（不含引号）。

Sample Input

【输入样例1】
4 5
1 2 19 1
2 3 8 12
2 4 12 15
1 3 17 8
3 4 1 17
【输入样例2】
3 1
1 2 1 1

Sample Output

【输出样例1】

32
【样例说明1】
如果小E走路径1→2→4，需要携带19+15=34个守护精灵；
如果小E走路径1→3→4，需要携带17+17=34个守护精灵；
如果小E走路径1→2→3→4，需要携带19+17=36个守护精灵；
如果小E走路径1→3→2→4，需要携带17+15=32个守护精灵。
综上所述，小E最少需要携带32个守护精灵。
【输出样例2】
-1
【样例说明2】
小E无法从1号节点到达3号节点，故输出-1。

HINT

2<=n<=50,000

0<=m<=100,000

1<=ai ,bi<=50,000

Source

题解：

卡时真是一件痛苦的事儿。。考场上肯定卡不出来。。。

考场上怎么就sb的去枚举a，二分b，在spfa呢？更直观的想法不就是枚举a做mst吗？脑袋短路了。。。

正解是LCT，蒟蒻不会，先spfa水过。。

枚举a，做spfa即可，但这样只有30分，考虑各种优化：

1.每次枚举的时候 d 数组不用清空，如果 d[n]值发生了变化，一定走了一条当前枚举的 a 的上限，则每次用 d [n]+xx 来更新答案，如果没发生变化，也不会影响答案，因为xx是递增的

2.如果这样直接做的话会是答案错误，这是为什么？

  这是因为在加入了一条新边之后，不一定能更新从 1 出发的点，所以其他点就不会被加入队列，这条边就没用被用到！

  所以我们应当在枚举到一条边的时候，将这条边的两端打标记，spfa从这些有标记的点出发即可

3.发现TLE。。。

   如果打印出ans的变化值可以发现，在开始很长时间内ans都是 inf，也就是说 1 与 n 都不连通

   这样我们可以从小到大加入边，用并查集维护连通性，直到 1 与 n 第一次连通时，我们开始做 spfa，这样可以省掉一些无用的过程

综合以上3点，终于AC。。。

代码：

1.考场35分（真是RP啊。。。）

const inf=maxlongint>>2;maxn=100000+10;
type node=record
     from,go,next,v1,v2:longint;
     end;
var a,b,d1,d2,head,fa:array[0..maxn] of longint;
    q:array[0..10*maxn] of longint;
    e:array[0..maxn*2] of node;
    v:array[0..maxn] of boolean;
    i,j,xx,yy,ll,tot,rr,x,y,point,mid:longint;
    ans,n,m:int64;
    function find(x:longint):longint;
     begin
     if fa[x]<>x then fa[x]:=find(fa[x]);
     exit(fa[x]);
     end;
    function max(x,y:longint):longint;
     begin
     if x>y then exit(x) else exit(y);
     end;
procedure sort1(l,r:longint);
 var i,j,x,y:longint;
 begin
 i:=l;j:=r;x:=a[(i+j)>>1];
 repeat
  while a[i]>x do inc(i);
  while a[j]<x do dec(j);
  if i<=j then
   begin
   y:=a[i];a[i]:=a[j];a[j]:=y;
   inc(i);dec(j);
   end;
 until i>j;
 if i<r then sort1(i,r);
 if j>l then sort1(l,j);
 end;
procedure sort2(l,r:longint);
 var i,j,x,y:longint;
 begin
 i:=l;j:=r;x:=b[(i+j)>>1];
 repeat
  while b[i]<x do inc(i);
  while b[j]>x do dec(j);
  if i<=j then
   begin
   y:=b[i];b[i]:=b[j];b[j]:=y;
   inc(i);dec(j);
   end;
 until i>j;
 if i<r then sort2(i,r);
 if j>l then sort2(l,j);
 end;
procedure insert(x,y,z,w:longint);
 begin
 inc(tot);
 with e[tot] do
  begin
  from:=x;go:=y;next:=head[x];head[x]:=tot;v1:=z;v2:=w;
  end;
 end;
procedure spfa;
 var i,x,y,h,t,tmp1,tmp2:longint;
 begin
 for i:=1 to n do d1[i]:=inf;
 for i:=1 to n do d2[i]:=inf;
 fillchar(v,sizeof(v),false);
 h:=0;t:=1;q[1]:=1;d1[1]:=0;d2[1]:=0;
 while h<t do
  begin
  inc(h);
  x:=q[h];v[x]:=false;
  i:=head[x];
  while i<>0 do
   begin
   y:=e[i].go;
   tmp1:=max(d1[x],e[i].v1);
   tmp2:=max(d2[x],e[i].v2);
   if (tmp1<=xx) and (tmp2<=yy) and (tmp2<d2[y]) then
    begin
    d1[y]:=tmp1;d2[y]:=tmp2;
    if not(v[y]) then
     begin
     v[y]:=true;
     inc(t);q[t]:=y;
     end;
    end;
   i:=e[i].next;
   end;
  end;
 end;
procedure init;
 begin
 readln(n,m);
 for i:=1 to n do fa[i]:=i;
 for i:=1 to m do
  begin
  readln(x,y,a[i],b[i]);
  xx:=find(x);yy:=find(y);
  if xx<>yy then fa[xx]:=yy;
  insert(x,y,a[i],b[i]);insert(y,x,a[i],b[i]);
  end;
 sort1(1,m);
 sort2(1,m);
 end;
procedure work1;
 begin
 xx:=a[1];point:=1;
 while true do
  begin
  ll:=1;rr:=m;
  while ll<rr do
   begin
   mid:=(ll+rr)>>1;
   yy:=b[mid];
   spfa;
   if d2[n]<>inf then rr:=mid else ll:=mid+1;
   end;
  inc(point);
  while (point<=m) and (d1[n]<a[point]) do inc(point);
  if point>m then break;
  xx:=a[point];
  if d1[n]+d2[n]<ans then ans:=d1[n]+d2[n];
  end;
 writeln(ans);
 end;
procedure work2;
 begin
 for i:=1 to 100 do
  begin
   xx:=random(a[1])+1;
   yy:=random(b[m])+1;
   spfa;
   if d1[n]+d2[n]<ans then ans:=d1[n]+d2[n];
  end;
 writeln(ans);
 end;
begin
 assign(input,'forest.in');assign(output,'forest.out');
 reset(input);rewrite(output);
 init;
 ans:=inf;
 if find(1)<>find(n) then writeln('-1') else if n*m*16<50000000 then work1 else work2;
 close(input);close(output);
end.   

2.朴素SPFA55分

const inf=maxlongint>>2;maxn=100000+10;
type node=record
     from,go,next,v1,v2:longint;
     end;
var a,b,d1,d2,head,fa:array[0..maxn] of longint;
    q:array[0..10*maxn] of longint;
    e:array[0..maxn*2] of node;
    v:array[0..maxn] of boolean;
    i,j,xx,yy,l,tot,r,x,y:longint;
    ans,n,m:int64;
    function find(x:longint):longint;
     begin
     if fa[x]<>x then fa[x]:=find(fa[x]);
     exit(fa[x]);
     end;
    function max(x,y:longint):longint;
     begin
     if x>y then exit(x) else exit(y);
     end;
    function min(x,y:longint):longint;
     begin
     if x<y then exit(x) else exit(y);
     end;

procedure sort(l,r:longint);
 var i,j,x,y:longint;
 begin
 i:=l;j:=r;x:=a[(i+j)>>1];
 repeat
  while a[i]<x do inc(i);
  while a[j]>x do dec(j);
  if i<=j then
   begin
   y:=a[i];a[i]:=a[j];a[j]:=y;
   inc(i);dec(j);
   end;
 until i>j;
 if i<r then sort(i,r);
 if j>l then sort(l,j);
 end;
procedure insert(x,y,z,w:longint);
 begin
 inc(tot);
 with e[tot] do
  begin
  from:=x;go:=y;next:=head[x];head[x]:=tot;v1:=z;v2:=w;
  end;
 end;
procedure spfa;
 var i,x,y,h,t,tmp1,tmp2:longint;
 begin
 for i:=1 to n do d1[i]:=inf;
 for i:=1 to n do d2[i]:=inf;
 fillchar(v,sizeof(v),false);
 h:=0;t:=1;q[1]:=1;d1[1]:=0;d2[1]:=0;
 while h<t do
  begin
  inc(h);
  x:=q[h];v[x]:=false;
  i:=head[x];
  while i<>0 do
   begin
   y:=e[i].go;
   tmp1:=max(d1[x],e[i].v1);
   tmp2:=max(d2[x],e[i].v2);
   if (tmp1<=xx) and (tmp2<d2[y]) then
    begin
    d1[y]:=tmp1;d2[y]:=tmp2;
    if not(v[y]) then
     begin
     v[y]:=true;
     inc(t);q[t]:=y;
     end;
    end;
   i:=e[i].next;
   end;
  end;
 end;
procedure init;
 begin
 readln(n,m);
 for i:=1 to n do fa[i]:=i;
 for i:=1 to m do
  begin
  readln(x,y,a[i],b[i]);
  xx:=find(x);yy:=find(y);
  if xx<>yy then fa[xx]:=yy;
  insert(x,y,a[i],b[i]);insert(y,x,a[i],b[i]);
  end;
 sort(1,m);
 end;
procedure work1;
 begin
 xx:=a[1];l:=0;r:=m;
 while true do
  begin
  while a[l]=a[l-1] do inc(l);
  inc(l);xx:=a[l];
  if l>r then break;
  spfa;
  while d1[n]+d2[n]<=a[r] do dec(r);
  ans:=min(ans,d1[n]+d2[n]);
  xx:=a[r];
  spfa;
  ans:=min(ans,d1[n]+d2[n]);
  while d1[n]<=a[r] do dec(r);
  end;
 writeln(ans);
 end;
begin
 assign(input,'forest.in');assign(output,'forest.out');
 reset(input);rewrite(output);
 init;
 ans:=inf;
 if find(1)<>find(n) then writeln('-1') else work1;
 close(input);close(output);
end.      

3.MST40分

const inf=maxlongint>>2;maxn=100000+10;
type node=record
     from,go,next,v1,v2:longint;
     end;
     arr=array[0..maxn] of longint;
var a,b,c,d,head,fa,aa:arr;
    e:array[0..maxn*2] of node;
    v,hash:array[0..maxn] of boolean;
    i,j,xx,yy,l,tot,r,x,y,cnt:longint;
    ans,n,m:int64;
    flag:boolean;
    function find(x:longint):longint;
     begin
     if fa[x]<>x then fa[x]:=find(fa[x]);
     exit(fa[x]);
     end;
    function max(x,y:longint):longint;
     begin
     if x>y then exit(x) else exit(y);
     end;
    function min(x,y:longint):longint;
     begin
     if x<y then exit(x) else exit(y);
     end;
procedure swap(var x,y:longint);
 var t:longint;
 begin
 t:=x;x:=y;y:=t;
 end;

procedure sort(l,r:longint);
 var i,j,x:longint;
 begin
 i:=l;j:=r;x:=aa[(i+j)>>1];
 repeat
  while aa[i]<x do inc(i);
  while aa[j]>x do dec(j);
  if i<=j then
   begin
   swap(aa[i],aa[j]);
   inc(i);dec(j);
   end;
 until i>j;
 if i<r then sort(i,r);
 if j>l then sort(l,j);
 end;
procedure sort1(l,r:longint);
 var i,j,x:longint;
 begin
 i:=l;j:=r;x:=b[(i+j)>>1];
 repeat
  while b[i]<x do inc(i);
  while b[j]>x do dec(j);
  if i<=j then
   begin
   swap(a[i],a[j]);swap(b[i],b[j]);swap(c[i],c[j]);swap(d[i],d[j]);
   inc(i);dec(j);
   end;
 until i>j;
 if i<r then sort1(i,r);
 if j>l then sort1(l,j);
 end;
procedure insert(x,y,z,w:longint);
 begin
 inc(tot);
 with e[tot] do
  begin
  from:=x;go:=y;next:=head[x];head[x]:=tot;v1:=z;v2:=w;
  end;
 end;
procedure init;
 begin
 readln(n,m);
 for i:=1 to n do fa[i]:=i;
 for i:=1 to m do
  begin
  readln(x,y,a[i],b[i]);
  xx:=find(x);yy:=find(y);
  if xx<>yy then fa[xx]:=yy;
  c[i]:=x;d[i]:=y;
  end;
 aa:=a;
 sort(1,m);sort1(1,m);
 end;
procedure dfs(x,t1,t2:longint);
 var i,y:longint;
 begin
 v[x]:=true;
 if x=n then begin flag:=true;ans:=min(ans,t1+t2);exit;end;
 i:=head[x];
 while i<>0 do
  begin
  y:=e[i].go;
  if not(v[y]) then dfs(y,max(t1,e[i].v1),max(t2,e[i].v2));
  if flag then break;
  i:=e[i].next;
  end;
 end;
procedure mst;
 var i,j:longint;
 begin
 fillchar(v,sizeof(v),false);
 fillchar(head,sizeof(head),0);tot:=0;
 for i:=1 to n do fa[i]:=i;
 j:=1;
 for i:=1 to n-1 do
  begin
  while (j<=m) and ((a[j]>xx) or (find(d[j])=find(c[j])))do inc(j);
  if j>m then exit;
  fa[find(d[j])]:=find(c[j]);
  insert(c[j],d[j],a[j],b[j]);insert(d[j],c[j],a[j],b[j]);
  end;
 //for i:=1 to n do writeln(head[i]);
 flag:=false;
 dfs(1,0,0);
 end;
procedure work1;
 begin
 //for i:=1 to m do write(aa[i],' ');writeln;
 l:=0;r:=m;
 while true do
  begin
  inc(l);
  while aa[l]=aa[l-1] do inc(l);//writeln(l,' ',aa[l],' ',r);
  inc(cnt);
  if l>r then break;
  xx:=aa[l];
  mst;
  while ans<=aa[r] do dec(r);
  inc(cnt);
  xx:=aa[r];
  mst;
  dec(r);while aa[r]=aa[r+1] do dec(r);
  end;
 writeln(ans);
 end;
procedure work2;
 begin
 fillchar(hash,sizeof(hash),false);
 for i:=1 to 200 do
   begin
   repeat
    x:=random(m)+1;
   until not(hash[aa[x]]);
   xx:=aa[x];
   mst;
   end;
 writeln(ans);
 end;

begin
 assign(input,'forest.in');assign(output,'forest.out');
 reset(input);rewrite(output);
 randomize;
 init;
 ans:=inf;
 if find(1)<>find(n) then writeln('-1')
 else if n*m<20000000 then work1 else work2;
 close(input);close(output);
end.  

4.SPFA优化80分

const inf=maxlongint>>2;maxn=100000+10;
type node=record
     from,go,next,v1,v2:longint;
     end;
var a,b,d,c1,c2,head,fa:array[0..maxn] of longint;
    q:array[0..10*maxn] of longint;
    e:array[0..maxn*2] of node;
    v:array[0..maxn] of boolean;
    i,j,xx,yy,l,z,w,tot,r,x,y:longint;
    ans,n,m,mm:int64;
    function find(x:longint):longint;
     begin
     if fa[x]<>x then fa[x]:=find(fa[x]);
     exit(fa[x]);
     end;
    function max(x,y:longint):longint;
     begin
     if x>y then exit(x) else exit(y);
     end;
    function min(x,y:longint):longint;
     begin
     if x<y then exit(x) else exit(y);
     end;
    procedure swap(var x,y:longint);
     var t:longint;
     begin
     t:=x;x:=y;y:=t;
     end;

procedure sort(l,r:longint);
 var i,j,x:longint;
 begin
 i:=l;j:=r;x:=a[(i+j)>>1];
 repeat
  while a[i]<x do inc(i);
  while a[j]>x do dec(j);
  if i<=j then
   begin
   swap(a[i],a[j]);swap(b[i],b[j]);swap(c1[i],c1[j]);swap(c2[i],c2[j]);
   inc(i);dec(j);
   end;
 until i>j;
 if i<r then sort(i,r);
 if j>l then sort(l,j);
 end;
procedure insert(x,y,z,w:longint);
 begin
 inc(tot);
 with e[tot] do
  begin
  from:=x;go:=y;next:=head[x];head[x]:=tot;v1:=z;v2:=w;
  end;
 end;
procedure spfa;
 var i,x,y,h,t,tmp:longint;
 begin
 h:=0;t:=0;
 for i:=1 to n do if v[i] then begin inc(t);q[t]:=i;end;
 //for i:=1 to t do writeln(q[i]);
 while h<t do
  begin
  inc(h);
  x:=q[h];v[x]:=false;
  i:=head[x];
  while i<>0 do
   begin
   y:=e[i].go;
   tmp:=max(d[x],e[i].v2);
   //writeln(e[i].v1,' ',xx,' ',tmp,' ',d[y]);
   if (e[i].v1<=xx) and (tmp<d[y]) then
    begin
    d[y]:=tmp;//writeln(d[y]);
    if not(v[y]) then
     begin
     v[y]:=true;
     inc(t);q[t]:=y;
     end;
    end;
   i:=e[i].next;
   end;
  end;
 end;
procedure init;
 begin
 readln(n,m);mm:=m;m:=0;
 for i:=1 to n do fa[i]:=i;
 for i:=1 to mm do
  begin
  readln(x,y,z,w);
  xx:=find(x);yy:=find(y);
  if xx<>yy then fa[xx]:=yy;
  if x=y then continue;
  inc(m);c1[m]:=x;c2[m]:=y;a[m]:=z;b[m]:=w;
  insert(x,y,z,w);insert(y,x,z,w);
  end;
 sort(1,m);
// for i:=1 to m do writeln(c1[i],' ',c2[i],' ',a[i],' ',b[i]);
 end;
procedure main;
 begin
 d[1]:=0;
 for i:=2 to n do d[i]:=inf;
 //for i:=1 to n do writeln(i,' ',d[i],' ',head[i]);
 l:=1;r:=m;
 while true do
  begin
  fillchar(v,sizeof(v),false);
  while a[l]=a[l+1] do
   begin
   v[c1[l]]:=true;v[c2[l]]:=true;
   inc(l);
   end;
  v[c1[l]]:=true;v[c2[l]]:=true;
  xx:=a[l]; //writeln(xx);
  if l>r then break;
  spfa;
  //for i:=1 to n do writeln(i,' ',d[i]);
  //if d[n]+xx=19923 then writeln(c1[l],' ',c2[l],' ',a[l],' ',b[l]);
  //writeln(d[n],' ',xx);
  ans:=min(ans,d[n]+xx);// writeln(d[n],' ',l,' ',r,' ',xx);
  while ans<=a[r] do dec(r);
  inc(l);
  end;
 writeln(ans);
 end;
begin
 assign(input,'forest.in');assign(output,'forest.out');
 reset(input);rewrite(output);
 init;
 ans:=inf<<1;
 if find(1)<>find(n) then writeln('-1') else main;
 close(input);close(output);
end.   

5.SPFA再优化75分。。。

const inf=maxlongint>>2;maxn=100000+10;
type node=record
     from,go,next,v1,v2:longint;
     end;
var a,b,d,c1,c2,head,fa:array[0..maxn] of longint;
    q:array[0..10*maxn] of longint;
    e:array[0..maxn*2] of node;
    v:array[0..maxn] of boolean;
    i,j,xx,yy,l,z,w,tot,r,x,y:longint;
    ans,n,m,mm:int64;
    function find(x:longint):longint;
     begin
     if fa[x]<>x then fa[x]:=find(fa[x]);
     exit(fa[x]);
     end;
    function max(x,y:longint):longint;
     begin
     if x>y then exit(x) else exit(y);
     end;
    function min(x,y:longint):longint;
     begin
     if x<y then exit(x) else exit(y);
     end;
    procedure swap(var x,y:longint);
     var t:longint;
     begin
     t:=x;x:=y;y:=t;
     end;

procedure sort(l,r:longint);
 var i,j,x:longint;
 begin
 i:=l;j:=r;x:=a[(i+j)>>1];
 repeat
  while a[i]<x do inc(i);
  while a[j]>x do dec(j);
  if i<=j then
   begin
   swap(a[i],a[j]);swap(b[i],b[j]);swap(c1[i],c1[j]);swap(c2[i],c2[j]);
   inc(i);dec(j);
   end;
 until i>j;
 if i<r then sort(i,r);
 if j>l then sort(l,j);
 end;
procedure insert(x,y,z,w:longint);
 begin
 inc(tot);
 with e[tot] do
  begin
  from:=x;go:=y;next:=head[x];head[x]:=tot;v1:=z;v2:=w;
  end;
 end;
procedure spfa;
 var i,x,y,h,t,tmp:longint;
 begin
 h:=0;t:=0;
 for i:=1 to n do if v[i] then begin inc(t);q[t]:=i;end;
 //for i:=1 to t do writeln(q[i]);
 while h<t do
  begin
  inc(h);
  x:=q[h];v[x]:=false;
  i:=head[x];
  while i<>0 do
   begin
   y:=e[i].go;
   tmp:=max(d[x],e[i].v2);
   //writeln(e[i].v1,' ',xx,' ',tmp,' ',d[y]);
   if (e[i].v1<=xx) and (tmp<d[y]) then
    begin
    d[y]:=tmp;//writeln(d[y]);
    if not(v[y]) then
     begin
     v[y]:=true;
     inc(t);q[t]:=y;
     end;
    end;
   i:=e[i].next;
   end;
  end;
 end;
procedure init;
 begin
 readln(n,m);mm:=m;m:=0;
 for i:=1 to n do fa[i]:=i;
 for i:=1 to mm do
  begin
  readln(x,y,z,w);
  xx:=find(x);yy:=find(y);
  if xx<>yy then fa[xx]:=yy;
  //if x=y then continue;
  inc(m);c1[m]:=x;c2[m]:=y;a[m]:=z;b[m]:=w;
  insert(x,y,z,w);insert(y,x,z,w);
  end;
 sort(1,m);
// for i:=1 to m do writeln(c1[i],' ',c2[i],' ',a[i],' ',b[i]);
 end;
procedure main;
 begin
 d[1]:=0;
 for i:=2 to n do d[i]:=inf;
 //for i:=1 to n do writeln(i,' ',d[i],' ',head[i]);
 l:=1;r:=m;
 for i:=1 to n do fa[i]:=i;
 while find(1)<>find(n) do begin fa[find(c1[l])]:=find(c2[l]);inc(l);end;
 //writeln(l,' ',find(1),' ',find(n));
 while a[l]=a[l-1] do inc(l);
 v[1]:=true;xx:=a[l-1];spfa;ans:=min(ans,d[n]+xx);
 while true do
  begin
  fillchar(v,sizeof(v),false);
  while a[l]=a[l+1] do
   begin
   v[c1[l]]:=true;v[c2[l]]:=true;
   inc(l);
   end;
  v[c1[l]]:=true;v[c2[l]]:=true;
  xx:=a[l]; //writeln(xx);
  if l>r then break;
  spfa;
  //for i:=1 to n do writeln(i,' ',d[i]);
  //if d[n]+xx=19923 then writeln(c1[l],' ',c2[l],' ',a[l],' ',b[l]);
  //writeln(d[n],' ',xx);
  ans:=min(ans,d[n]+xx);// writeln(d[n],' ',l,' ',r,' ',xx);
  while ans<=a[r] do dec(r);
  inc(l);
  end;
 writeln(ans);
 end;
begin
 assign(input,'forest.in');assign(output,'forest.out');
 reset(input);rewrite(output);
 init;
 ans:=inf<<1;
 if find(1)<>find(n) then writeln('-1') else main;
 close(input);close(output);
end.    

6.原来发现数组开小了。。。100分，苦逼的调试

const inf=maxlongint>>2;maxn=100000+10;
type node=record
     from,go,next,v1,v2:longint;
     end;
var a,b,d,c1,c2,head,fa:array[0..maxn] of longint;
    q:array[0..100*maxn] of longint;
    e:array[0..maxn*2] of node;
    v:array[0..maxn] of boolean;
    i,j,xx,yy,l,z,w,tot,r,x,y:longint;
    ans,n,m,mm:int64;
    function find(x:longint):longint;
     begin
     if fa[x]<>x then fa[x]:=find(fa[x]);
     exit(fa[x]);
     end;
    function max(x,y:longint):longint;
     begin
     if x>y then exit(x) else exit(y);
     end;
    function min(x,y:longint):longint;
     begin
     if x<y then exit(x) else exit(y);
     end;
    procedure swap(var x,y:longint);
     var t:longint;
     begin
     t:=x;x:=y;y:=t;
     end;

procedure sort(l,r:longint);
 var i,j,x:longint;
 begin
 i:=l;j:=r;x:=a[(i+j)>>1];
 repeat
  while a[i]<x do inc(i);
  while a[j]>x do dec(j);
  if i<=j then
   begin
   swap(a[i],a[j]);swap(b[i],b[j]);swap(c1[i],c1[j]);swap(c2[i],c2[j]);
   inc(i);dec(j);
   end;
 until i>j;
 if i<r then sort(i,r);
 if j>l then sort(l,j);
 end;
procedure insert(x,y,z,w:longint);
 begin
 inc(tot);
 with e[tot] do
  begin
  from:=x;go:=y;next:=head[x];head[x]:=tot;v1:=z;v2:=w;
  end;
 end;
procedure spfa;
 var i,x,y,h,t,tmp:longint;
 begin
 //writeln(1);
 h:=0;t:=0;
 for i:=1 to n do if v[i] then begin inc(t);q[t]:=i;end;
 //for i:=1 to t do writeln(q[i]);
 while h<t do
  begin
  inc(h);
  x:=q[h];v[x]:=false; //writeln(x);
  i:=head[x];
  while i<>0 do
   begin
   y:=e[i].go;
   tmp:=max(d[x],e[i].v2);
   //writeln(e[i].v1,' ',xx,' ',tmp,' ',d[y]);
   if (e[i].v1<=xx) and (tmp<d[y]) then
    begin
    d[y]:=tmp;//writeln(d[y]);
    if not(v[y]) then
     begin
     v[y]:=true;
     inc(t);q[t]:=y;
     end;
    end;
   i:=e[i].next;
   end;
  end;
 end;
procedure init;
 begin
 readln(n,m);mm:=m;m:=0;
 for i:=1 to n do fa[i]:=i;
 for i:=1 to mm do
  begin
  readln(x,y,z,w);
  xx:=find(x);yy:=find(y);
  if xx<>yy then fa[xx]:=yy;
  if x=y then continue;
  inc(m);c1[m]:=x;c2[m]:=y;a[m]:=z;b[m]:=w;
  insert(x,y,z,w);insert(y,x,z,w);
  end;
 sort(1,m);//writeln(m);
 //for i:=1 to m do writeln(i,' ',c1[i],' ',c2[i],' ',a[i],' ',b[i]);
 end;
procedure main;
 begin
 d[1]:=0;
 for i:=2 to n do d[i]:=inf;
 //for i:=1 to n do writeln(i,' ',d[i],' ',head[i]);
 l:=1;r:=m;
 for i:=1 to n do fa[i]:=i;
 while find(1)<>find(n) do
  begin
  //writeln(l,' ',find(1),' ',find(n));
  //writeln(c1[l],' ',c2[l]);
  xx:=find(c1[l]);yy:=find(c2[l]);
  if xx<>yy then fa[xx]:=yy;
  inc(l);
  end;
 //writeln(l,' ',find(1),' ',find(n));
 while a[l]=a[l-1] do inc(l);//writeln(l);
 v[1]:=true;xx:=a[l-1];//writeln(xx);
 spfa;
 //for i:=1 to n do writeln(i,' ',d[i]);
 ans:=min(ans,d[n]+xx);//writeln('            ',ans);
 while true do
  begin
  //writeln('         ',ans);
  fillchar(v,sizeof(v),false);
  if l>r then break;
  while a[l]=a[l+1] do
   begin
   v[c1[l]]:=true;v[c2[l]]:=true;
   inc(l);
   end;
  v[c1[l]]:=true;v[c2[l]]:=true;
  xx:=a[l]; //writeln(xx);
  if l>r then break;
  spfa;
  //for i:=1 to n do writeln(i,' ',d[i]);
  //if d[n]+xx=19923 then writeln(c1[l],' ',c2[l],' ',a[l],' ',b[l]);
  //writeln(d[n],' ',xx);
  ans:=min(ans,d[n]+xx);//writeln(d[n],' ',l,' ',r,' ',xx);
  while ans<=a[r] do dec(r);
  inc(l);
  end;
 writeln(ans);
 end;
begin
 assign(input,'forest.in');assign(output,'forest.out');
 reset(input);rewrite(output);
 init;
 ans:=inf<<1;
 if find(1)<>find(n) then writeln('-1') else main;
 close(input);close(output);
end.  

7.去掉调试更清晰。。。

const inf=maxlongint>>2;maxn=100000+10;
type node=record
     from,go,next,v1,v2:longint;
     end;
var a,b,d,c1,c2,head,fa:array[0..maxn] of longint;
    q:array[0..100*maxn] of longint;
    e:array[0..maxn*2] of node;
    v:array[0..maxn] of boolean;
    i,j,xx,yy,l,z,w,tot,r,x,y:longint;
    ans,n,m,mm:int64;
    function find(x:longint):longint;
     begin
     if fa[x]<>x then fa[x]:=find(fa[x]);
     exit(fa[x]);
     end;
    function max(x,y:longint):longint;
     begin
     if x>y then exit(x) else exit(y);
     end;
    function min(x,y:longint):longint;
     begin
     if x<y then exit(x) else exit(y);
     end;
    procedure swap(var x,y:longint);
     var t:longint;
     begin
     t:=x;x:=y;y:=t;
     end;

procedure sort(l,r:longint);
 var i,j,x:longint;
 begin
 i:=l;j:=r;x:=a[(i+j)>>1];
 repeat
  while a[i]<x do inc(i);
  while a[j]>x do dec(j);
  if i<=j then
   begin
   swap(a[i],a[j]);swap(b[i],b[j]);swap(c1[i],c1[j]);swap(c2[i],c2[j]);
   inc(i);dec(j);
   end;
 until i>j;
 if i<r then sort(i,r);
 if j>l then sort(l,j);
 end;
procedure insert(x,y,z,w:longint);
 begin
 inc(tot);
 with e[tot] do
  begin
  from:=x;go:=y;next:=head[x];head[x]:=tot;v1:=z;v2:=w;
  end;
 end;
procedure spfa;
 var i,x,y,h,t,tmp:longint;
 begin
 h:=0;t:=0;
 for i:=1 to n do if v[i] then begin inc(t);q[t]:=i;end;
 while h<t do
  begin
  inc(h);
  x:=q[h];v[x]:=false;
  i:=head[x];
  while i<>0 do
   begin
   y:=e[i].go;
   tmp:=max(d[x],e[i].v2);
   if (e[i].v1<=xx) and (tmp<d[y]) then
    begin
    d[y]:=tmp;
    if not(v[y]) then
     begin
     v[y]:=true;
     inc(t);q[t]:=y;
     end;
    end;
   i:=e[i].next;
   end;
  end;
 end;
procedure init;
 begin
 readln(n,m);mm:=m;m:=0;
 for i:=1 to n do fa[i]:=i;
 for i:=1 to mm do
  begin
  readln(x,y,z,w);
  xx:=find(x);yy:=find(y);
  if xx<>yy then fa[xx]:=yy;
  if x=y then continue;
  inc(m);c1[m]:=x;c2[m]:=y;a[m]:=z;b[m]:=w;
  insert(x,y,z,w);insert(y,x,z,w);
  end;
 sort(1,m);

 end;
procedure main;
 begin
 d[1]:=0;
 for i:=2 to n do d[i]:=inf;
 l:=1;r:=m;
 for i:=1 to n do fa[i]:=i;
 while find(1)<>find(n) do
  begin
  xx:=find(c1[l]);yy:=find(c2[l]);
  if xx<>yy then fa[xx]:=yy;
  inc(l);
  end;
 while a[l]=a[l-1] do inc(l);
 v[1]:=true;xx:=a[l-1];
 spfa;
 ans:=min(ans,d[n]+xx);
 while true do
  begin
  fillchar(v,sizeof(v),false);
  if l>r then break;
  while a[l]=a[l+1] do
   begin
   v[c1[l]]:=true;v[c2[l]]:=true;
   inc(l);
   end;
  v[c1[l]]:=true;v[c2[l]]:=true;
  xx:=a[l];
  if l>r then break;
  spfa;
  ans:=min(ans,d[n]+xx);
  while ans<=a[r] do dec(r);
  inc(l);
  end;
 writeln(ans);
 end;
begin
 assign(input,'forest.in');assign(output,'forest.out');
 reset(input);rewrite(output);
 init;
 ans:=inf<<1;
 if find(1)<>find(n) then writeln('-1') else main;
 close(input);close(output);
end.