题意:给出1~n的一个序列,求区间最大值-区间最小值<k的区间数。
RMQ处理出区间最大最小值,易知某段区间的最大值-其最小值会随着区间长度的减小而减小,因此可以通过枚举左端点,二分右端点来计算以左端点为起点的区间满足条件的贡献。
#include <bits/stdc++.h>
#include <map>
#include <set>
#include <queue>
#include <stack>
#include <cmath>
#include <time.h>
#include <vector>
#include <cstdio>
#include <string>
#include <iomanip>
///cout << fixed << setprecision(13) << (double) x << endl;
#include <cstdlib>
#include <cstring>
#include <iostream>
#include <algorithm>
using namespace std;
#define lson l, mid, rt << 1
#define rson mid + 1, r, rt << 1 | 1
#define ls rt << 1
#define rs rt << 1 | 1
#define pi acos(-1.0)
#define eps 1e-8
#define Mp(a, b) make_pair(a, b)
#define asd puts("asdasdasdasdasdf");
typedef long long ll;
//typedef __int64 LL;
const int inf = 0x3f3f3f3f;
const int N = 101000;
int dp1[N][20];
int dp2[N][20];
int LOG[N];
int a[N];
void init_LOG()
{
LOG[0] = -1;
for( int i = 1; i <= N-10; ++i )
LOG[i] = ( (i&(i-1) ) == 0 ) ? LOG[i-1] + 1 : LOG[i-1];
}
void init_RMQ( int n )
{
for( int i = 1; i <= n; ++i )
dp1[i][0] = dp2[i][0] = a[i];
for( int j = 1; j <= LOG[n]; ++j ) {
for( int i = 1; i + ( 1 << j ) - 1 <= n; ++i ) {
dp1[i][j] = max( dp1[i][j-1], dp1[i+(1<<(j-1))][j-1] );
dp2[i][j] = min( dp2[i][j-1], dp2[i+(1<<(j-1))][j-1] );
}
}
}
int cal( int l, int r )
{
int k = LOG[r-l+1];
int maxx = max( dp1[l][k], dp1[r-(1<<k)+1][k] );
int minn = min( dp2[l][k], dp2[r-(1<<k)+1][k] );
return maxx - minn;
}
int main()
{
init_LOG();
int tot, k, n;
for( scanf("%d", &tot); tot--; ) {
scanf("%d%d", &n, &k);
for( int i = 1; i <= n; ++i ) {
scanf("%d", &a[i]);
}
init_RMQ(n);
ll ans = 0;
for( int i = 1; i <= n; ++i ) {
ll l = i, r = n, mid;
while( l <= r ) {
mid = (l+r) >> 1;
ll tmp = cal( i, mid );
if( tmp < k )
l = mid+1;
else
r = mid-1;
}
ll len = l - i;
ans += len;
}
printf("%lld\n", ans);
}
return 0;
}