Algorithm Sum All Numbers In A Range - ashish9342/FreeCodeCamp GitHub Wiki
🚩 Remember to use Read-Search-Ask
if you get stuck. Try to pair program 👥 and write your own code 📝
You need to create a program that will take an array of two numbers who are not necessarily in order, and then add not just those numbers but any numbers in between. For example, [3,1] will be the same as 1+2+3
and not just 3+1
Use Math.max()
to find the maximum value of two numbers.
try to solve the problem now
Use Math.min()
to find the minimum value of two numbers.
try to solve the problem now
Remember to that you must add all the numbers in between so this would require a way to get those numbers.
try to solve the problem now
Solution ahead!
function sumAll(arr) {
var max = Math.max(arr[0], arr[1]);
var min = Math.min(arr[0], arr[1]);
var temp = 0;
for (var i=min; i <= max; i++){
temp += i;
}
return(temp);
}
sumAll([1, 4]);
🚀 Run Code
- First create a variable to store the max number between two.
- The same as before for the Smallest number.
- We create a temporary variable to add the numbers.
Since the numbers might not be always in order, using max()
and min()
will help organize.
function sumAll(arr) {
// Buckle up everything to one!
// Using ES6 arrow function (one-liner)
var sortedArr = arr.sort((a,b) => a-b);
var firstNum = arr[0];
var lastNum = arr[1];
// Using Arithmetic Progression summing formula
var sum = (lastNum - firstNum + 1) * (firstNum + lastNum) / 2;
return sum;
}
🚀 Run Code
- Firstly, we create a variable called
sortedArr
which sorts it from the lowest to the highest value. -
firstNum
is equal to the first number andlastNum
is equal to the second number. - Next, using the Arithmetic Progression summing formula we let
sum
equal(lastNum - firstNum + 1) * (firstNum + lastNum) / 2
. - Finally, we return
sum
.
The line var sortedArr = arr.sort((a,b) => a-b);
is probably what will have you more confused. This would be the same as creating a function that returns a-b
for the sort()
which is the standard way to sort numbers from smallest to largest. Instead using arrow or fat arrow function, we are able to do all that in one single line thus allowing us to write less.
function sumAll(arr) {
var sum = 0;
for (var i = Math.min(...arr); i <= Math.max(...arr); i++){
sum += i;
}
return sum;
}
sumAll([1, 4]);
🚀 Run Code
- Creating a variable sum to store the sum of the elements.
- Starting iteration of the loop from min element of given array and stopping when it reaches the max element.
- Using a spread operator (...arr) allows passing the actual array to the function instead of one-by-one elements.
If you found this page useful, you can give thanks by copying and pasting this on the main chat:
Thanks @Rafase282 @abhisekp for your help with Algorithm: Sum All Numbers in a Range
⚠️ DO NOT add solutions that are similar to any existing solutions. If you think it is similar but better, then try to merge (or replace) the existing similar solution.- Add an explanation of your solution.
- Categorize the solution in one of the following categories — Basic, Intermediate and Advanced. 🚥
- Please add your username only if you have added any relevant main contents. (:warning: DO NOT remove any existing usernames)
See 👉
Wiki Challenge Solution Template
for reference.