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

 1 /**************************************************************
 2     Problem: 3381
 3     User: HansBug
 4     Language: Pascal
 5     Result: Accepted
 6     Time:272 ms
 7     Memory:2220 kb
 8 ****************************************************************/
 9  
10 var
11    i,j,k,l,m,n,h:longint;
12    a:array[0..30000,0..16] of longint;
13 function min(x,y:longint):longint;
14          begin
15               if x<y then min:=x else min:=y;
16          end;
17 begin
18      readln(n,m);
19      h:=trunc(ln(n)/ln(2)+1);
20      for i:=1 to n do readln(a[i,0]);
21      for i:=1 to h do
22          for j:=1 to n-trunc(exp(ln(2)*i))+1 do
23              a[j,i]:=min(a[j,i-1],a[j+trunc(exp(ln(2)*(i-1))),i-1]);
24  
25      for i:=1 to m do
26          begin
27               readln(j,k);
28               l:=trunc(ln(k-j+1)/ln(2));
29               writeln(min(a[j,l],a[k-trunc(exp(ln(2)*l))+1,l]));
30          end;
31      readln;
32 end.