要求

題目

We'll pass you an array of two numbers. Return the sum of those two numbers and all numbers between them.
The lowest number will not always come first.
Remember to use Read-Search-Ask if you get stuck. Try to pair program. Write your own code.

Here are some helpful links:

• Math.max()

• Math.min()

• Array.prototype.reduce()

given code

function sumAll(arr) {
  return 1;
}
sumAll([1, 4]);

分析

分別獲取最大值和最小值，然后依次相加

• 獲取最大值
• 獲取最小值
• 從小到大依次相加

 function sumAll(arr) {
    var max = Math.max(arr[0],arr[1]);
    var min = Math.min(arr[0],arr[1]);
  return (max+min)*(max-min+1)/2;
}
sumAll([1, 4]);