exercise2.md

Exercise

Description:

Given an array arr that contains some integers(positive, negative or 0), and a range list such as [[start1,end1],[start2,end2],...], start and end are the index of arr and start always less than end. Your task is calculte the sum value of each range, and return the maximum sum value.

For example:

Given arr = [1,-2,3,4,-5,-4,3,2,1], range = [[1,3],[0,4],[6,8]] should return 6

calculte process: range[1,3] = arr[1]+arr[2]+arr[3] = 5 range[0,4] = arr[0]+arr[1]+arr[2]+arr[3]+arr[4] = 1 range[6,8] = arr[6]+arr[7]+arr[8] = 6 So the maximum sum value is 6

Note:

arr always has at least 5 elements;

range always has at least 1 elements;

All inputs are valid;

Test Examples:

maxSum([1,-2,3,4,-5,-4,3,2,1],[[1,3],[0,4],[6,8]]) === 6

maxSum([1,-2,3,4,-5,-4,3,2,1],[[1,3]]) === 5

maxSum([1,-2,3,4,-5,-4,3,2,1],[[1,4],[2,5]]) === 0

Solution

function maxSum(arr,range){
  let maxArr = range.map(rarr => arr.slice(rarr[0],rarr[1]+1).reduce((prev, next) => prev + next, 0));
  return Math.max(...maxArr);
}