hdu5289 Assignment (interval query maximum minimum value, ST algorithm ...)

Title: http://acm.hdu.edu.cn/showproblem.php?pid=5289

Test instructions: Given a sequence of length n and an integer k, find the interval between the maximum and minimum values less than K. Outputs the number of intervals that satisfy the condition.

Analysis: Enumeration A[i], to A[i] as the starting point, and then two points to find the end (large interval to meet the conditions of the Community must also meet), according to the location of the starting point and the end can be calculated to a[i] as the starting point to meet the conditions of the number of intervals. How to infer whether the interval satisfies the condition? The ST algorithm can be used to preprocess the O (N*logn) method, and then the O (1) query interval maximum can be the minimum value. The previous query timed out with the segment tree:

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Later I saw others using the tree-like array + two points too.

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There is a queue to write, or Direct line tree not two points ....

Code:

#include <iostream> #include <cstdio>using namespace std; #define Lson L,m,rt<<1#define Rson m+1,r,rt <<1|1const int maxn = 2e5;int _max,_min,n,k;int max[100006][20],min[100006][20],a[100006];void Init () {int i,j; for (i=0;i<n;i++) max[i][0]=min[i][0]=a[i];for (j=1; (1<<j) <=n;j++) {for (i=0;i+ (1<<j) -1<n;i++) {max[i][j]=max[i][j-1]>max[i+ (1<< (j-1))][j-1]? max[i][j-1]:max[i+ (1<< (j-1))][j-1]; min[i][j]=min[i][j-1]<min[i+ (1<< (j-1))][j-1]?
min[i][j-1]:min[i+ (1<< (j-1))][j-1];}}} bool OK (int l,int R) {int K=0;while ((1<< (k+1)) <= (r-l+1)) k++;_min=min[l][k]<min[r-(1<<k) +1][k]? min[l][k]:min[r-(1<<k) +1][k];_max=max[l][k]>max[r-(1<<k) +1][k]? max[l][k]:max[r-(1<<k) +1][k];return _max-_min<k;} int Find (int s) {int down=s+1,up=n-1,mid,ret=s;while (down<=up) {mid= (down+up) >>1;if (!ok (s,mid)) up=mid-1; Else{down=mid+1;if (Ret<mid) Ret=mid;}} return ret;} int main () {int ncase,i,j;long long ans;scanf ("%d", &ncase), while (ncase--) {scanf ('%d%d ', &n,&k); for (i=0;i <n;i++) scanf ("%d", &a[i]); Init (); Ans=n;for (i=0;i<n;i++) ans+=find (i)-i;printf ("%i64d\n", ans);} return 0;}

hdu5289 Assignment (interval query maximum minimum value, ST algorithm ...)