POJ 3264 Balanced Lineup（RMQ）

Balanced Lineup

Description

For the daily milking, Farmer John‘s N cows (1 ≤ N ≤ 50,000) always line up in the same order. One day Farmer John decides to organize a game of Ultimate Frisbee with some of the cows. To keep things simple, he will take a contiguous range of cows from the milking lineup to play the game. However, for all the cows to have fun they should not differ too much in height.

Farmer John has made a list of Q (1 ≤ Q ≤ 200,000) potential groups of cows and their heights (1 ≤ height ≤ 1,000,000). For each group, he wants your help to determine the difference in height between the shortest and the tallest cow in the group.

Input

Line 1: Two space-separated integers, N and Q.
Lines 2..N+1: Line i+1 contains a single integer that is the height of cow i

Lines N+2..N+Q+1: Two integers A and B (1 ≤ A ≤ B ≤ N), representing the range of cows from A to B inclusive.

Output

Lines 1..Q:
Each line contains a single integer that is a response to a reply and
indicates the difference in height between the tallest and shortest cow
in the range.

Sample Input

6 3
1
7
3
4
2
5
1 5
4 6
2 2

Sample Output

6
3
0

求区间最大最小值差

#include <iostream>
#include <cstdio>
#include <cstring>
#include <string>
#include <cmath>
#include <vector>
#include <queue>
#include <map>
#include <set>
#include <stack>
#include <algorithm>
using namespace std;
#define root 1,n,1
#define lson l,mid,rt<<1
#define rson mid+1,r,rt<<1|1
#define lr rt<<1
#define rr rt<<1|1
typedef long long LL;
const int oo = 1e9+7;
const double PI = acos(-1.0);
const double eps = 1e-6 ;
const int N =  50010;
const int mod = 2333333;
int dp_m[N][20] , dp_M[N][20] , mm[N] , b[N] , n , m ;
void initRMQ( int n ) {
    mm[0] = -1 ;
    for( int i = 1 ; i <= n ; ++i ){
        mm[i] = ( (i&(i-1)) ==0 )?mm[i-1]+1:mm[i-1];
        dp_m[i][0]=dp_M[i][0]=b[i];
    }
    for(int j = 1 ; j <= mm[n] ; ++j ) {
        for( int i = 1 ; i+(1<<j)-1<=n ; ++i ) {
            dp_M[i][j] = max( dp_M[i][j-1] ,dp_M[i+(1<<(j-1))][j-1]);
            dp_m[i][j] = min( dp_m[i][j-1] ,dp_m[i+(1<<(j-1))][j-1]);
        }
    }
}
int rmq( int x , int y ){
    int k = mm[y-x+1];
    return max(dp_M[x][k],dp_M[y-(1<<k)+1][k]) - min(dp_m[x][k],dp_m[y-(1<<k)+1][k]) ;
}

int main()
{
    #ifdef LOCAL
        freopen("in.txt","r",stdin);
//        freopen("out.txt","w",stdout);
    #endif // LOCAL
    int _ ,x ,y , c ;
    while( ~scanf("%d%d",&n,&m) ) {
        for( int i =1 ; i <= n ; ++i ){
            scanf("%d",&b[i]);
        }
        initRMQ(n);
        while(m--) {
            scanf("%d%d",&x,&y);
            printf("%d\n",rmq(x,y));
        }
    }
}