92 lines
3.9 KiB
Markdown
92 lines
3.9 KiB
Markdown
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# Dog and Gopher
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A large field has a dog and a gopher.
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The dog wants to eat the gopher, while the gopher wants to run to safety through one of several gopher holes dug in the surface ofthe field.
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Neither the dog nor the gopher is a math major; however, neither is entirely stupid.
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The gopher decides on a particular gopher hole and heads for that hole in a straight line at a fixed speed. The dog, which is very good at reading body language, anticipates which hole the gopher has chosen.
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The dog heads at double the speed of the gopher to the hole. If the dog reaches the hole first, the gopher gets gobbled up; otherwise, the gopher escapes.
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## Objective
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You have been retained by the gopher to **select a hole through which it can escape**, if such a hole exists, by **reading a file with a variable set of scenarios**.
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Some sample files are already provided to help the tests:
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```text
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assets/day-35_sample_1_valid.txt
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assets/day-35_sample_2_valid.txt
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assets/day-35_sample_3_invalid.txt
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assets/day-35_sample_4_invalid.txt
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assets/day-35_sample_5_invalid.txt
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assets/day-35_sample_6_invalid.txt
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```
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Write a **gopherEscapePlan** function which returns a list/array of strings, with one entry per result of each set of scenarios.
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The function has one input parameter:
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- **filename**: a string representing the path to the file
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The function returns:
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- List/array of strings, with one entry per result of each set of scenarios or a BAD FILE! message if the file is invalid or inaccessible. See section **Output** below for more details.
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## Input file format
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The input file contains several sets of input. The first line of each set contains **one integer** and **four floating point numbers**.
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The integer **n** denotes how many holes are in the set.
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The **four floating point numbers** denote the **(x, y) coordinates of the gopher** followed by the **(x, y) coordinates of the dog**.
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The subsequent **n** lines of input each contain **two floating point numbers**: the **(x, y) coordinates of a gopher hole**. All distances are in meters to the nearest millimeter.
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The input is **terminated by end of file** and **there is a blank line between two consecutive sets**.
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The input file is still considered **valid** if there is more than one **blank line between two consecutive sets** or if there are **blank lines at the beginning of the file** as well.
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## Output
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Return a single line for *each set* of input.
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If the gopher can escape, the output line should read, _“The gopher can escape through the hole at (x, y).”_ while identifying the appropriate hole to the nearest millimeter.
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Otherwise, the output line should read, _“The gopher cannot escape.”_
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If the gopher can escape through more than one hole, report the one that appears **first in the input**.
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if the file is **inaccessible or invalid** (for example, **number of holes** found don't match **n** or there are more or less fields found on a line in the file), return just an **["BAD FILE!"]**.
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## Constraints
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There are at most 1,000 gopher holes in a set of input and all coordinates range between –10,000 and +10,000.
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### Example of input file
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```text
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1.000 1.000 2.000 2.000
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1.500 1.500
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2 2.000 2.000 1.000 1.000
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1.500 1.500
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2.500 2.500
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```
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### Expected return
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```text
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["The gopher cannot escape.", "The gopher can escape through the hole at (2.500,2.500)."]
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```
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### Examples with the provided sample files avaliable at 'assets' folder
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```text
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gopherEscapePlan("...assets/day-35_sample_1_valid.txt") ➞ ["The gopher cannot escape.", "The gopher can escape through the hole at (2.500000,2.500000)."]
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gopherEscapePlan("...assets/day-35_sample_2_valid.txt") ➞ ["The gopher cannot escape.", "The gopher can escape through the hole at (2.500000,2.500000)."]
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gopherEscapePlan("...assets/day-35_sample_3_invalid.txt") ➞ ["BAD FILE!"]
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gopherEscapePlan("...assets/day-35_sample_4_invalid.txt") ➞ ["BAD FILE!"]
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gopherEscapePlan("...assets/day-35_sample_5_invalid.txt") ➞ ["BAD FILE!"]
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```
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