The problems below have been taken from CodingBat’s Python Exercises, while all solutions were written by me. I’ve used go fmt and conducted tests for my codes, but please don’t hold it against me if I’ve missed a few edge cases somewhere. All solutions are licensed under MIT.


String-1

String-1 provided opportunities for me to define functions inside a separate function, as well as create functions that returned multiple values. Other than that, the problems were predominantly solvable with language agnostic solutions.

hello_name

Given a string name, e.g. “Bob”, return a greeting of the form “Hello Bob!”.

func hello_name(str string) string {
    return "Hello " + str + "!"
}

make_abba

Given two strings, a and b, return the result of putting them together in the order abba, e.g. “Hi” and “Bye” returns “HiByeByeHi”.

func make_abba(a, b string) string {
    return a + b + b + a
}

make_tags

The web is built with HTML strings like “Yay” which draws Yay as italic text. In this example, the “i” tag makes and which surround the word “Yay”. Given tag and word strings, create the HTML string with tags around the word, e.g. “Yay”.

func make_tags(tag, word string) string {
    start := func(tag string) string {
        return "<" + tag + ">"
    }
    end := func(tag string) string {
        return "</" + tag + ">"
    }
    return start(tag) + word + end(tag)
}

make_out_word

Given an “out” string length 4, such as “«»”, and a word, return a new string where the word is in the middle of the out string, e.g. “«word»”.

func make_out_word(out, word string) string {
    return out[0:2] + word + out[2:]
}

extra_end

Given a string, return a new string made of 3 copies of the last 2 chars of the original string. The string length will be at least 2.

func extra_end(str string) string {
    return str[len(str)-2:] + str[len(str)-2:] + str[len(str)-2:]
}

first_two

Given a string, return the string made of its first two chars, so the String “Hello” yields “He”. If the string is shorter than length 2, return whatever there is, so “X” yields “X”, and the empty string “” yields the empty string “”.

func first_two(str string) string {
    if len(str) < 2 {
        return str
    }

    return str[0:2]
}

first_half

Given a string of even length, return the first half. So the string “WooHoo” yields “Woo”.

func first_half(str string) string {
    return str[:len(str)/2]
}

without_end

Given a string, return a version without the first and last char, so “Hello” yields “ell”. The string length will be at least 2.

func without_end(str string) string {
    return str[1 : len(str)-1]
}

combo_string

Given 2 strings, a and b, return a string of the form short+long+short, with the shorter string on the outside and the longer string on the inside. The strings will not be the same length, but they may be empty (length 0).

func combo_string(a, b string) string {
    compare_strings := func(a, b string) (string, string) {
        if len(a) < len(b) {
            return a, b
        }
        return b, a
    }

    short, long := compare_strings(a, b)

    return short + long + short
}

non_start

Given 2 strings, return their concatenation, except omit the first char of each. The strings will be at least length 1.

func non_start(a, b string) string {
    return a[1:] + b[1:]
}

left2

Given a string, return a “rotated left 2” version where the first 2 chars are moved to the end. The string length will be at least 2.

func left2(str string) string {
    return str[2:] + str[:2]
}

List-1

List-1 covers array and slice manipulation. The solutions are mostly language agnostic, so there’s nothing much to see if you’re not entirely new to programming.

first_last6

Given an array of ints, return True if 6 appears as either the first or last element in the array. The array will be length 1 or more.

func first_last6(nums []int) bool {
    return nums[0] == 6 || nums[len(nums)-1] == 6
}

same_first_last

Given an array of ints, return True if the array is length 1 or more, and the first element and the last element are equal.

func same_first_last(nums []int) bool {
    if len(nums) > 1 {
        return nums[0] == nums[len(nums)-1]
    }

    return false
}

make_pi

Return an int array length 3 containing the first 3 digits of pi, {3, 1, 4}.

func make_pi() []int {
    return []int{3, 1, 4}
}

common_end

Given 2 arrays of ints, a and b, return True if they have the same first element or they have the same last element. Both arrays will be length 1 or more.

func common_end(a, b []int) bool {
    return a[0] == b[0] || a[len(a)-1] == b[len(b)-1]
}

sum3

Given an array of ints length 3, return the sum of all the elements.

func sum3(nums []int) int {
    return nums[0] + nums[1] + nums[2]
}

rotate_left3

Given an array of ints length 3, return an array with the elements “rotated left” so {1, 2, 3} yields {2, 3, 1}.

func rotate_left3(nums []int) []int {
    return append(nums[2:3], nums[:2]...)
}

reverse3

Given an array of ints length 3, return a new array with the elements in reverse order, so {1, 2, 3} becomes {3, 2, 1}.

func reverse3(nums []int) []int {
    return []int{nums[2], nums[1], nums[0]}
}

max_end3

Given an array of ints length 3, figure out which is larger between the first and last elements in the array, and set all the other elements to be that value. Return the changed array.

func max_end3(nums []int) []int {
    max := int(math.Max(float64(nums[0]), float64(nums[2])))
    return []int{max, max, max}
}

sum2

Given an array of ints, return the sum of the first 2 elements in the array. If the array length is less than 2, just sum up the elements that exist, returning 0 if the array is length 0.

func sum2(nums []int) int {
    var count int = 0
    if len(nums) < 2 {
        for _, val := range nums {
            count += val
        }
        return count
    }

    return nums[0] + nums[2]
}

middle_way

Given 2 int arrays, a and b, each length 3, return a new array length 2 containing their middle elements.

func middle_way(a, b []int) []int {
    return []int{a[1], b[1]}
}

make_ends

Given an array of ints, return a new array length 2 containing the first and last elements from the original array. The original array will be length 1 or more.

func make_ends(nums []int) []int {
    return []int{nums[0], nums[len(nums)-1]}
}

has23

Given an int array length 2, return True if it contains a 2 or a 3.

func has23(nums []int) bool {
    for _, val := range nums {
        if val == 2 || val == 3 {
            return true
        }
    }
    return false
}