Sorting a Segment

AtCoder

IDagc038_b

Time2000ms

Memory256MB

Difficulty—

Snuke has a permutation $(P_0,P_1,\cdots,P_{N-1})$ of $(0,1,\cdots,N-1)$. Now, he will perform the following operation **exactly once**: * Choose $K$ consecutive elements in $P$ and sort them in ascending order. Find the number of permutations that can be produced as $P$ after the operation. ## Constraints * $2 \leq N \leq 200000$ * $2 \leq K \leq N$ * $0 \leq P_i \leq N-1$ * $P_0,P_1,\cdots,P_{N-1}$ are all different. * All values in input are integers. ## Input Input is given from Standard Input in the following format: $N$ $K$ $P_0$ $P_1$ $\cdots$ $P_{N-1}$ [samples]

Samples

Input #1

5 3
0 2 1 4 3

Output #1

2

Two permutations can be produced as $P$ after the operation: $(0,1,2,4,3)$ and $(0,2,1,3,4)$.

Input #2

4 4
0 1 2 3

Output #2

Input #3

10 4
2 0 1 3 7 5 4 6 8 9

Output #3

API Response (JSON)

{
  "problem": {
    "name": "Sorting a Segment",
    "description": {
      "content": "Snuke has a permutation $(P_0,P_1,\\cdots,P_{N-1})$ of $(0,1,\\cdots,N-1)$. Now, he will perform the following operation **exactly once**: *   Choose $K$ consecutive elements in $P$ and sort them in as",
      "description_type": "Markdown"
    },
    "platform": "AtCoder",
    "limit": {
      "time_limit": 2000,
      "memory_limit": 262144
    },
    "difficulty": "None",
    "is_remote": true,
    "is_sync": true,
    "sync_url": null,
    "sign": "agc038_b"
  },
  "statements": [
    {
      "statement_type": "Markdown",
      "content": "Snuke has a permutation $(P_0,P_1,\\cdots,P_{N-1})$ of $(0,1,\\cdots,N-1)$.\nNow, he will perform the following operation **exactly once**:\n\n*   Choose $K$ consecutive elements in $P$ and sort them in as...",
      "is_translate": false,
      "language": "English"
    }
  ]
}

Full JSON Raw Segments