Intro 🌐
Problem solving is an important skill, for your career and your life in general.
That's why I take interesting katas of all levels, customize them and explain how to solve them.
Understanding the Exercise❗
First, we need to understand the exercise!
If you don't understand it, you can't solve it!.
My personal method:
- Input: What do I put in?
- Output: What do I want to get out?
Today's exercise
Today, we'll have a look at our first 7 kyu
kata,
meaning we slightly increase the difficulty.
Source: Codewars
Write a function everyPossibleSum
, that accepts one parameter: myNumber
.
Given a number, e.g. 1234
,
return every possible sum of two digits, e.g. [ 3, 4, 5, 5, 6, 7 ]
.
For this example, we calculate:
[ 1 + 2, 1 + 3, 1 + 4, 2 + 3, 2 + 4, 3 + 4 ]
Input: a number.
Output: an array of numbers.
Thinking about the Solution 💭
I think I understand the exercise (= what I put into the function and what I want to get out of it).
Now, I need the specific steps to get from input to output.
I try to do this in small baby steps:
- Get the single digits of the input number
- Go to the first digit and find all sums with each next digit, starting from the second
- Go to the second digit and find all sums with each next digit, starting from the third
- Do this for every digit
- Return the array with each sum in it
Example:
- Input:
1234
- Go to the first digit and find all sums with each next digit, starting from the second:
1 + 2
,1 + 3
,1 + 4
- Go to the second digit and find all sums with each next digit, starting from the third:
2 + 3
,2 + 4
- Do this for every digit:
3 + 4
- Return the array with each sum in it:
[ 3, 4, 5, 5, 6, 7 ]
- Output:
[ 3, 4, 5, 5, 6, 7 ]
✅
Implementation ⛑
function everyPossibleSum(myNumber) {
// split up number into its digits
const split = String(myNumber) // make it a string
.split("") // split it
.map((digit) => Number(digit)); // convert each split char to a number
const sums = [];
// first number: iterate from the first to the last number
for (let first = 0; first < split.length; first++) {
// second number: iterate from the next number after the current first number to the last number
for (let second = first + 1; second < split.length; second++) {
// save the sum in the sums array
sums.push(split[first] + split[second]);
}
}
return sums;
}
Result
console.log(everyPossibleSum(1234));
// [ 3, 4, 5, 5, 6, 7 ] ✅
console.log(everyPossibleSum(81596));
// [ 9, 13, 17, 14, 6, 10, 7, 14, 11, 15 ] ✅
Playground ⚽
You can play around with the code here
Next Part ➡️
Great work!
We learned how to use String
, split
, map
, for
.
I hope you can use your new learnings to solve problems more easily!
Next time, we'll solve another interesting kata. Stay tuned!
If I should solve a specific kata, shoot me a message here.
If you want to read my latest stuff, get in touch with me!
Further Reading 📖
Questions ❔
- How often do you do katas?
- Which implementation do you like more? Why?
- Any alternative solution?
Top comments (0)