POJ 3264 Balanced Lineup 简单RMQ

#include <stdio.h>
#include <algorithm>
#include <math.h>

int dpMin[50010][31], dpMax[50010][31];

int RMinQ(int l, int r)
{
int k = log(1.0 * r-l+1)/log(2.0);
return std::min(dpMin[l][k], dpMin[r-(1<<k)+1][k]);
}

int RMaxQ(int l, int r)
{
int k = log(1.0 * r-l+1)/log(2.0);
return std::max(dpMax[l][k], dpMax[r-(1<<k)+1][k]);
}

int main()
{
int n, m;
scanf("%d %d", &n, &m);
for(int i = 1; i <= n; i++)
{
scanf("%d", &dpMin[i][0]);
dpMax[i][0] = dpMin[i][0];
}
for(int j = 1; (1<<j) <= n; j++)
{
for(int i = 0; i + (1<<j) - 1 <= n; i++)
{
dpMax[i][j] = std::max(dpMax[i][j-1], dpMax[i+(1<<(j-1))][j-1]);
dpMin[i][j] = std::min(dpMin[i][j-1], dpMin[i+(1<<(j-1))][j-1]);
}
}
int x, y;
while(m--)
{
scanf("%d %d", &x, &y);
printf("%d\n", RMaxQ(x, y) - RMinQ(x, y));
}
return 0;
}