3381: [Usaco2004 Open]Cave Cows 2 洞穴里的牛之二

3381: [Usaco2004 Open]Cave Cows 2 洞穴里的牛之二

Time Limit: 10 Sec  Memory Limit: 128 MB
Submit: 21  Solved: 18
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Description

    洞窟里有一道长长的通道．它由N(1≤N≤25000)段道尾相连构成，编号分别为1到N．每个通道有一个阈值，其范围在[1，10^9]依次通过i..j的通道，那奶牛的体重指数就不能超过i..j通道中阈值的最小值．贝茜有Q(1≤Q≤25000)个问题，想请教你由i到j的通道的阈值的最小值．

Input

    第1行输入N和Q，接下来N行输入每个通道的阈值，之后Q行每行两个整数，对应问题中的i和j（i<j）．

Output

   对于每个问题，输出其结果．

Sample Input

10 4
75
30
100
38
50
51
52
20
81
5
1 10
3 5
6 9
8 10

Sample Output

5
38
20
5

HINT

 

Source

Orange

 

题解：RMQ模板题。。。感觉自己水水哒

/**************************************************************
    Problem: 3381
    User: HansBug
    Language: Pascal
    Result: Accepted
    Time:272 ms
    Memory:2220 kb
****************************************************************/
 
var
   i,j,k,l,m,n,h:longint;
   a:array[0..30000,0..16] of longint;
function min(x,y:longint):longint;
         begin
              if x<y then min:=x else min:=y;
         end;
begin
     readln(n,m);
     h:=trunc(ln(n)/ln(2)+1);
     for i:=1 to n do readln(a[i,0]);
     for i:=1 to h do
         for j:=1 to n-trunc(exp(ln(2)*i))+1 do
             a[j,i]:=min(a[j,i-1],a[j+trunc(exp(ln(2)*(i-1))),i-1]);
 
     for i:=1 to m do
         begin
              readln(j,k);
              l:=trunc(ln(k-j+1)/ln(2));
              writeln(min(a[j,l],a[k-trunc(exp(ln(2)*l))+1,l]));
         end;
     readln;
end.