Resistors in Parallel

AtCoder

IDabc138_b

Time2000ms

Memory256MB

Difficulty—

Given is a sequence of $N$ integers $A_1, \ldots, A_N$. Find the (multiplicative) inverse of the sum of the inverses of these numbers, $\frac{1}{\frac{1}{A_1} + \ldots + \frac{1}{A_N}}$. ## Constraints * $1 \leq N \leq 100$ * $1 \leq A_i \leq 1000$ ## Input Input is given from Standard Input in the following format: $N$ $A_1$ $A_2$ $\ldots$ $A_N$ [samples]

Samples

Input #1

2
10 30

Output #1

7.5

$\frac{1}{\frac{1}{10} + \frac{1}{30}} = \frac{1}{\frac{4}{30}} = \frac{30}{4} = 7.5$.
Printing `7.50001`, `7.49999`, and so on will also be accepted.

Input #2

3
200 200 200

Output #2

66.66666666666667

$\frac{1}{\frac{1}{200} + \frac{1}{200} + \frac{1}{200}} = \frac{1}{\frac{3}{200}} = \frac{200}{3} = 66.6666...$.
Printing `6.66666e+1` and so on will also be accepted.

Input #3

1
1000

Output #3

1000

$\frac{1}{\frac{1}{1000}} = 1000$.
Printing `+1000.0` and so on will also be accepted.

API Response (JSON)

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    "name": "Resistors in Parallel",
    "description": {
      "content": "Given is a sequence of $N$ integers $A_1, \\ldots, A_N$. Find the (multiplicative) inverse of the sum of the inverses of these numbers, $\\frac{1}{\\frac{1}{A_1} + \\ldots + \\frac{1}{A_N}}$.",
      "description_type": "Markdown"
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    "platform": "AtCoder",
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      "memory_limit": 262144
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  "statements": [
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      "statement_type": "Markdown",
      "content": "Given is a sequence of $N$ integers $A_1, \\ldots, A_N$.\nFind the (multiplicative) inverse of the sum of the inverses of these numbers, $\\frac{1}{\\frac{1}{A_1} + \\ldots + \\frac{1}{A_N}}$.\n\n## Constrain...",
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Full JSON Raw Segments