> For the complete documentation index, see [llms.txt](https://anton-veselskyi.gitbook.io/codding-problems-solutions/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://anton-veselskyi.gitbook.io/codding-problems-solutions/codewars/6-kyu/tortoise-racing.md).

# Tortoise racing

## [Tortoise racing](https://www.codewars.com/kata/55e2adece53b4cdcb900006c)

Two tortoises named ***A*** and ***B*** must run a race. ***A*** starts with an average speed of `720 feet per hour`. Young ***B*** knows she runs faster than ***A***, and furthermore has not finished her cabbage.

When she starts, at last, she can see that ***A*** has a `70 feet lead` but ***B***'s speed is `850 feet per hour`. How long will it take ***B*** to catch ***A***?

More generally: given two speeds `v1` (***A***'s speed, integer > 0) and `v2` (***B***'s speed, integer > 0) and a lead `g` (integer > 0) how long will it take ***B*** to catch ***A***?

The result will be an array `[hour, min, sec]` which is the time needed in hours, minutes and seconds (round down to the nearest second) or a string in some languages.

If `v1 >= v2` then return `nil`, `nothing`, `null`, `None` or `{-1, -1, -1}` for C++, C, Go, Nim, `[]` for Kotlin or "-1 -1 -1".

## Examples:

(form of the result depends on the language)

```
race(720, 850, 70) => [0, 32, 18] or "0 32 18"
race(80, 91, 37)   => [3, 21, 49] or "3 21 49"
```

\*\* Note:

* See other examples in "Your test cases".
* In Fortran - as in any other language - the returned string is not permitted to contain any redundant trailing whitespace: you can use dynamically allocated character strings.

\*\* Hints for people who don't know how to convert to hours, minutes, seconds:

* Tortoises don't care about fractions of seconds
* Think of calculation by hand using only integers (in your code use or simulate integer division)
* or Google: "convert decimal time to hours minutes seconds"

## Solutions

### 👴 C

```c
int* race(int v1, int v2, int g)
{
  int * res = (int*)malloc(sizeof(int)*3);
  if (v1 >= v2)
  {
    res[0]=-1;res[1]=-1;res[2]=-1;
    return res;
  }

  double delta_time = 1.0,
  S = g,
  how_long_to_get = 0; //in hours
  while(delta_time > 0.0000000001) // 3.6e-07 sec
  {
    delta_time =  S / (double)v2;
    S = v1 * delta_time;
    how_long_to_get+=delta_time;
  }

  how_long_to_get+=0.00000001;
  res[0] = (int)how_long_to_get; //hours
  res[1] = (how_long_to_get - res[0]) * 60; // mins
  res[2] = (how_long_to_get - res[0] - res[1]/60.0) * 3600; //secs

  return res;
}
```


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter:

```
GET https://anton-veselskyi.gitbook.io/codding-problems-solutions/codewars/6-kyu/tortoise-racing.md?ask=<question>&goal=<endgoal>
```

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal.

The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.