Sum Numbers in a range

1

Hello, I just solved the sum all numbers in a range challenge but I got a strange behavior in the process

I first did this…

var total = 0;
function sumAll(arr) {
  var min = Math.min.apply(null, arr);
  var max = Math.max.apply(null, arr);

  for(var i = min; i <= max; i++){
    total += i;
  }

  return total;
}
sumAll([5, 10]);

only the first test that checks if the output is a number passed, though the outputs were correct. However, when I did the following, which is basically changing the scope of the total variable, it was accepted

function sumAll(arr) {
  var min = Math.min.apply(null, arr);
  var max = Math.max.apply(null, arr);
  var total = 0;

  for(var i = min; i <= max; i++){
    total += i;
  }

  return total;
}
sumAll([5, 10]);

WHY???

3

This is what I did. It works.

function sumAll(arr) {
  var sum = 0;
  if(arr[1]>arr[0]){
  for(var i = arr[0]; i <= arr[1]; i++){
    sum = sum + i;
    }
  }
  else{
    for(var j = arr[0]; j >= arr[1]; j--){
    sum = sum + j;
    }
  }
  return sum;
}

sumAll([4, 1]);
5

congrats.I will try with this later.

6

I am wandering if there is a way to create the numbers without using for.....

I mean for example using map. Because as I understood map method return an array with the same input length..... 

function sumAll(arr) {
let data = ([].concat(arr)).sort((a,b)=>a-b);
let newData = []

for (let i = data[0];i<=data[1];i++){
 newData.push(i)
}
return(newData.reduce((a,b)=>a +b));

}

sumAll([1, 4]);
7

There is also a mathematical formula for adding all numbers from X to Y, which is very useful here, and lets you avoid a for loop completely.

(highestNumber - lowestNumber + 1) * (highestNumber + lowestNumber) / 2
8

aww wow… that’s genius i understood ur solution perfectly. good job!