POJ_3264_Balanced Lineup

很裸的RMQ~

#include<iostream>

#include<cstdio>

#include<cstring>

#include<cmath>

#include<algorithm>

#include<string>

#include<queue>

using namespace std;

#define MAXN 50005

int maxsum[MAXN][20],minsum[MAXN][20],n,q;

void RMQ()

{

    for(int j=1;(1<<j)<=n;++j)

        for(int i=1;i+(1<<j)-1<=n;++i)

        {

            maxsum[i][j]=max(maxsum[i][j-1],maxsum[i+(1<<(j-1))][j-1]);

            minsum[i][j]=min(minsum[i][j-1],minsum[i+(1<<(j-1))][j-1]);

        }

}

int main()

{

    int i,j,k,L,R;

   while(~scanf("%d%d",&n,&q))

   {

       for(i=1;i<=n;++i)

       {

           scanf("%d",&maxsum[i][0]);

           minsum[i][0]=maxsum[i][0];

       }

       RMQ();

       while(q--)

       {

           scanf("%d%d",&L,&R);

           int k=(int)((log(R-L+1.0))/log(2.0));

           int maxval=max(maxsum[L][k],maxsum[R-(1<<k)+1][k]);

           int minval=min(minsum[L][k],minsum[R-(1<<k)+1][k]);

           printf("%d\n",maxval-minval);

       }

   }

   return 0;

}