RMQ

1 D

void initRMQ(int n)
{
        int MAX=(int)log2(n);
	FOR(i,1,n)
	{
		f[i][0]=a[i];
	}
	FOR(j,1,MAX)
	{
		FOR(i,1,n) if (i+(1<<(j-1))<=n)
		{
			f[i][j]=max(f[i][j-1],f[i+(1<<(j-1))][j-1]);
		}
	}    
}
int getRMQ(int x,int y)
{
	int k=(int)log2(y-x+1);
	return max(f[x][k],f[y-(1<<(k))+1][k]);
}

two D

void initRMQ(int n,int m)
{
//        leave out init a[i][j][0][0]
	int Maxn=(int)log2(n);
	int Maxm=(int)log2(m);
	FOR(ii,0,Maxn)
	{
		FOR(jj,0,Maxm)
		{
			if (ii+jj)
			{
				FOR(i,1,n) if (i+(1<<ii)-1<=n)
				{
					FOR(j,1,m) if (j+(1<<jj)-1<=m)
					{
						if (ii==0)
						{
							f[i][j][ii][jj]=max(f[i][j][ii][jj-1],f[i][j+(1<<(jj-1))][ii][jj-1]);
						}
						else
						{
							f[i][j][ii][jj]=max(f[i][j][ii-1][jj],f[i+(1<<(ii-1))][j][ii-1][jj]);
						}
					}
				}
			}
		}
	 } 
}
int getRMQ(int x1,int y1,int x2,int y2)//x1,y1:upleft
{
	int k1=(int)log2((x2-x1+1));
	int k2=(int)log2((y2-y1+1));
	int tmp1=f[x1][y1][k1][k2];
	int tmp2=f[x2-(1<<k1)+1][y2-(1<<k2)+1][k1][k2];
	int tmp3=f[x2-(1<<k1)+1][y1][k1][k2];
	int tmp4=f[x1][y2-(1<<k2)+1][k1][k2];
	int maxx=max(max(tmp1,tmp2),max(tmp3,tmp4));
	return maxx;
}