Swappable

AtCoder

IDabc206_c

Time2000ms

Memory256MB

Difficulty—

Given an array of $N$ integers $A=(A_1,A_2,...,A_N)$, find the number of pairs $(i,j)$ of integers satisfying all of the following conditions: * $1 \le i < j \le N$ * $A_i \neq A_j$ ## Constraints * All values in input are integers. * $2 \le N \le 3 \times 10^5$ * $1 \le A_i \le 10^9$ ## Input Input is given from Standard Input in the following format: $N$ $A_1$ $A_2$ $\dots$ $A_N$ [samples]

Samples

Input #1

3
1 7 1

Output #1

2

In this input, we have $A=(1,7,1)$.

*   For the pair $(1,2)$, $A_1 \neq A_2$.
*   For the pair $(1,3)$, $A_1 = A_3$.
*   For the pair $(2,3)$, $A_2 \neq A_3$.

Input #2

10
1 10 100 1000 10000 100000 1000000 10000000 100000000 1000000000

Output #2

Input #3

20
7 8 1 1 4 9 9 6 8 2 4 1 1 9 5 5 5 3 6 4

Output #3

API Response (JSON)

{
  "problem": {
    "name": "Swappable",
    "description": {
      "content": "Given an array of $N$ integers $A=(A_1,A_2,...,A_N)$, find the number of pairs $(i,j)$ of integers satisfying all of the following conditions: *   $1 \\le i < j \\le N$ *   $A_i \\neq A_j$",
      "description_type": "Markdown"
    },
    "platform": "AtCoder",
    "limit": {
      "time_limit": 2000,
      "memory_limit": 262144
    },
    "difficulty": "None",
    "is_remote": true,
    "is_sync": true,
    "sync_url": null,
    "sign": "abc206_c"
  },
  "statements": [
    {
      "statement_type": "Markdown",
      "content": "Given an array of $N$ integers $A=(A_1,A_2,...,A_N)$, find the number of pairs $(i,j)$ of integers satisfying all of the following conditions:\n\n*   $1 \\le i < j \\le N$\n*   $A_i \\neq A_j$\n\n## Constrain...",
      "is_translate": false,
      "language": "English"
    }
  ]
}

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