POJ 3264 Balanced Lineup ST table

POJ 3264 Balanced Lineup ST table

 

Question: Give a string of numbers and ask for the difference between the maximum and minimum values of the interval.

Train of Thought: For RMQ, we can use O (N ^ 2) preprocessing, and then each time we query O (1), we can use line segment tree and O (N) building, for O (logN) queries, you can use ST table records, O (NlogN) preprocessing, and O (1) queries.

In fact, the ST table preprocessing process is also a DP process. dp [I] [j] indicates the maximum range of 2 ^ j consecutive bits starting from the I bit.

Preprocessing: dp [I] [j] = min (dp [I] [j], dp [I + 2 ^ j] [j]), query: query (l, r) = min (dp [l] [k], dp [R-2 ^ k + 1] [k]), k guarantees 2 ^ k <= r-l + 1 and 2 ^ (k + 1)> = r-l + 1.

Code:

 

#include 
 
  #include 
  
   #include #define maxn 50010using namespace std;int stTable_min[maxn][32],stTable_max[maxn][32];int preLog2[maxn],aa[maxn];void st_prepare(int n,int *array){    preLog2[1]=0;    for(int i=2; i<=n; i++)    {        preLog2[i]=preLog2[i-1];        if((1<
   
=0; i--)    {        stTable_min[i][0]=array[i];        stTable_max[i][0]=array[i];        for(int j=1; (i+(1<