【CF652C】Foe Pairs（线性扫描）

 1 var f,c:array[1..310000]of int64;
 2     n,m,x,y,t:int64;
 3     i:longint;
 4     ans:int64;
 5 
 6 function min(x,y:int64):int64;
 7 begin
 8  if x<y then exit(x);
 9  exit(y);
10 end;
11 
12 begin
13  //assign(input,‘cf652C.in‘); reset(input);
14 // assign(output,‘cf652C.out‘); rewrite(output);
15  read(n,m);
16  for i:=1 to n do
17  begin
18   read(x);
19   c[x]:=i; f[i]:=n+1;
20  end;
21  ans:=n*(n+1) div 2;
22  for i:=1 to m do
23  begin
24   read(x,y);
25   if c[x]>c[y] then begin t:=x; x:=y; y:=t; end;
26   f[c[x]]:=min(f[c[x]],c[y]);
27  end;
28  for i:=n-1 downto 1 do f[i]:=min(f[i],f[i+1]);
29  for i:=1 to n-1 do ans:=ans-(n-f[i]+1);
30  writeln(ans);
31 // close(input);
32 // close(output);
33 end.