Index Trio

AtCoder

IDabc249_d

Time2000ms

Memory256MB

Difficulty—

You are given an integer sequence $A = (A_1, \dots, A_N)$ of length $N$. Find the number of triplets of integers $(i, j, k)$ satisfying all of the conditions below. * $1 \leq i, j, k \leq N$ * $\frac{A_i}{A_j} = A_k$ ## Constraints * $1 \leq N \leq 2 \times 10^5$ * $1 \leq A_i \leq 2 \times 10^5 \, (1 \leq i \leq N)$ * All values in input are integers. ## Input Input is given from Standard Input in the following format: $N$ $A_1$ $\ldots$ $A_N$ [samples]

Samples

Input #1

3
6 2 3

Output #1

2

$(i, j, k) = (1, 2, 3), (1, 3, 2)$ satisfy the conditions.

Input #2

1
2

Output #2

Input #3

10
1 3 2 4 6 8 2 2 3 7

Output #3

API Response (JSON)

{
  "problem": {
    "name": "Index Trio",
    "description": {
      "content": "You are given an integer sequence $A = (A_1, \\dots, A_N)$ of length $N$. Find the number of triplets of integers $(i, j, k)$ satisfying all of the conditions below. *   $1 \\leq i, j, k \\leq N$ *   $\\",
      "description_type": "Markdown"
    },
    "platform": "AtCoder",
    "limit": {
      "time_limit": 2000,
      "memory_limit": 262144
    },
    "difficulty": "None",
    "is_remote": true,
    "is_sync": true,
    "sync_url": null,
    "sign": "abc249_d"
  },
  "statements": [
    {
      "statement_type": "Markdown",
      "content": "You are given an integer sequence $A = (A_1, \\dots, A_N)$ of length $N$.\nFind the number of triplets of integers $(i, j, k)$ satisfying all of the conditions below.\n\n*   $1 \\leq i, j, k \\leq N$\n*   $\\...",
      "is_translate": false,
      "language": "English"
    }
  ]
}

Full JSON Raw Segments