P3381: [Usaco2004 Open]Cave Cows 2 洞穴里的牛之二

这题。。思维上远没有上一题复杂，是一个裸的RMQ。。利用倍增就可以解决了。

 1 var n,q,i,j,f,t,c:longint;
 2 a:array[0..20,0..25001] of longint;
 3 function min(a,b:longint):longint;
 4 begin
 5   if a>b then exit(b)
 6     else exit(a);
 7 end;
 8 begin
 9   readln(n,q);
10   for i:=1 to n do
11     readln(a[0,i]);
12   for i:=1 to trunc(ln(n)/ln(2))+1 do
13     for j:=1 to n-(1 shl i)+1 do
14       a[i,j]:=min(a[i-1,j],a[i-1,j+(1 shl (i-1))]);
15   for i:=1 to q do
16     begin
17       readln(f,t);
18       c:=trunc(ln(t-f+1)/ln(2));
19       writeln(min(a[c,f],a[c,t-(1 shl c)+1]));
20     end;
21 end.

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