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epequeno's solution

to Series in the Rust Track

Published at Dec 21 2018 · 0 comments
Test suite

Given a string of digits, output all the contiguous substrings of length n in that string in the order that they appear.

For example, the string "49142" has the following 3-digit series:

  • "491"
  • "914"
  • "142"

And the following 4-digit series:

  • "4914"
  • "9142"

And if you ask for a 6-digit series from a 5-digit string, you deserve whatever you get.

Note that these series are only required to occupy adjacent positions in the input; the digits need not be numerically consecutive.

Rust Installation

Refer to the exercism help page for Rust installation and learning resources.

Writing the Code

Execute the tests with:

$ cargo test

All but the first test have been ignored. After you get the first test to pass, open the tests source file which is located in the tests directory and remove the #[ignore] flag from the next test and get the tests to pass again. Each separate test is a function with #[test] flag above it. Continue, until you pass every test.

If you wish to run all tests without editing the tests source file, use:

$ cargo test -- --ignored

To run a specific test, for example some_test, you can use:

$ cargo test some_test

If the specific test is ignored use:

$ cargo test some_test -- --ignored

To learn more about Rust tests refer to the online test documentation

Make sure to read the Modules chapter if you haven't already, it will help you with organizing your files.

Feedback, Issues, Pull Requests

The exercism/rust repository on GitHub is the home for all of the Rust exercises. If you have feedback about an exercise, or want to help implement new exercises, head over there and create an issue. Members of the rust track team are happy to help!

If you want to know more about Exercism, take a look at the contribution guide.


A subset of the Problem 8 at Project Euler http://projecteuler.net/problem=8

Submitting Incomplete Solutions

It's possible to submit an incomplete solution so you can see how others have completed the exercise.


use series::*;

fn test_with_zero_length() {
    let expected = vec!["".to_string(); 6];
    assert_eq!(series("92017", 0), expected);

fn test_with_length_2() {
    let expected = vec![
    assert_eq!(series("92017", 2), expected);

fn test_with_numbers_length() {
    let expected = vec!["92017".to_string()];
    assert_eq!(series("92017", 5), expected);

fn test_too_long() {
    let expected: Vec<String> = vec![];
    assert_eq!(series("92017", 6), expected);
pub fn series(digits: &str, len: usize) -> Vec<String> {
    let mut ans = Vec::new();
    let chars: Vec<char> = digits.chars().collect();
    let mut i = 0;
    loop {
        let end = i + len;
        if end > digits.len() {
        } else {
            let s = &chars[i..end];
            let mut part = String::new();
            for c in s {
                part += &c.to_string();
        i += 1;

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