Ex - Beautiful Subsequences

AtCoder

IDabc248_h

Time6000ms

Memory256MB

Difficulty—

You are given a permutation $P=(P_1,\ldots,P_N)$ of $(1,\ldots,N)$, and an integer $K$. Find the number of pairs of integers $(L, R)$ that satisfy all of the following conditions: * $1 \leq L \leq R \leq N$ * $\mathrm{max}(P_L,\ldots,P_R) - \mathrm{min}(P_L,\ldots,P_R) \leq R - L + K$ ## Constraints * $1 \leq N \leq 1.4\times 10^5$ * $P$ is a permutation of $(1,\ldots,N)$. * $0 \leq K \leq 3$ * All values in input are integers. ## Input Input is given from Standard Input in the following format: $N$ $K$ $P_1$ $P_2$ $\ldots$ $P_N$ [samples]

Samples

Input #1

4 1
1 4 2 3

Output #1

9

The following nine pairs $(L, R)$ satisfy the conditions.

*   $(1,1)$
*   $(1,3)$
*   $(1,4)$
*   $(2,2)$
*   $(2,3)$
*   $(2,4)$
*   $(3,3)$
*   $(3,4)$
*   $(4,4)$

For $(L,R) = (1,2)$, we have $\mathrm{max}(A_1,A_2) -\mathrm{min}(A_1,A_2) = 4-1 = 3$ and $R-L+K=2-1+1 = 2$, not satisfying the condition.

Input #2

2 0
2 1

Output #2

Input #3

10 3
3 7 10 1 9 5 4 8 6 2

Output #3

API Response (JSON)

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      "content": "You are given a permutation $P=(P_1,\\ldots,P_N)$ of $(1,\\ldots,N)$, and an integer $K$.\nFind the number of pairs of integers $(L, R)$ that satisfy all of the following conditions:\n\n*   $1 \\leq L \\leq ...",
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