POJ 3264-Balanced Lineup-RMQ问题

裸RMQ问题

#include <cstdio>
#include <algorithm>
#include <cstring>

using namespace std;

const int MAXN = 50010;

int min_dp[MAXN][20],max_dp[MAXN][20];
int min_mm[MAXN],max_mm[MAXN];
int b[MAXN];
int N,Q;

void min_initRMQ(int n,int b[])
{
        min_mm[0] = -1;
        for(int i=1;i<=n;i++)
        {
                min_mm[i] = ( (i&(i-1)) == 0) ? min_mm[i-1]+1 : min_mm[i-1];
                min_dp[i][0] = b[i];
        }
        for(int j=1;j<=min_mm[n];j++)
                for(int i=1;i + (1<<j) - 1 <= n;i++)
                        min_dp[i][j] = min(min_dp[i][j-1],min_dp[i+(1<<(j-1))][j-1]);

}

int min_rmq(int x,int y)
{
        int k = min_mm[y-x+1];
        return min(min_dp[x][k],min_dp[y-(1<<k)+1][k]);
}


void max_initRMQ(int n,int b[])
{
        max_mm[0] = -1;
        for(int i=1;i<=n;i++)
        {
                max_mm[i] = ( (i&(i-1)) == 0) ? max_mm[i-1]+1 : max_mm[i-1];
                max_dp[i][0] = b[i];
        }
        for(int j=1;j<=max_mm[n];j++)
                for(int i=1;i + (1<<j) - 1 <= n;i++)
                        max_dp[i][j] = max(max_dp[i][j-1],max_dp[i+(1<<(j-1))][j-1]);

}

int max_rmq(int x,int y)
{
        int k = max_mm[y-x+1];
        return max(max_dp[x][k],max_dp[y-(1<<k)+1][k]);
}

int main()
{
        //freopen("input.in","r",stdin);
        while(~scanf("%d%d",&N,&Q))
        {
                for(int i=1;i<=N;i++)
                {
                    scanf("%d",&b[i]);
                }
                min_initRMQ(N,b);
                max_initRMQ(N,b);

                for(int i=0,l,r;i<Q;i++)
                {
                        scanf("%d%d",&l,&r);
                        printf("%d
",max_rmq(l,r) - min_rmq(l,r) );
                        //printf("%d
",max_rmq(l,r));
                }
        }
}