leetcode-1191.js

var kConcatenationMaxSum = function(arr, k) {
  let maxSum = calculateMaxSubArraySum(arr)
  if (k === 1) return maxSum
  
  let newArr = [...arr, ...arr]
  let sum = calculateMaxSubArraySum(newArr)
  
  if (sum <= maxSum) {
    return maxSum
  }
  
  maxSum = sum
  newArr = [...newArr, ...arr]
  sum = calculateMaxSubArraySum(newArr)
  
  if (sum <= maxSum) {
    return maxSum
  }
  
  return maxSum + (sum - maxSum) * (k - 1)
};

function calculateMaxSubArraySum(newArr) {
  let maxSum = 0
  for (let i=0; i < newArr.length; i++) {
    for (let j=i; j < newArr.length; j++) {
      let sum = 0
      for (let k=i; k <= j; k++) sum += newArr[k]
      if (sum > maxSum) {
        maxSum = sum
      }
    }
  }
  return maxSum;
}

Esta solución todavía no funciona. Ayuda!

Buenas noches, dejó mi aporte al problema

var kConcatenationMaxSum = function(arr, k) {
  let MOD=1000000007
  let n=arr.length

  const sumMax = (q,n)=>{
    let rep=0
    let sum=0
    let max=0
    while(rep<q){
      for(let i=0;i<n;i++){
        sum+=arr[i]
        sum=Math.max(0,sum)
        max=Math.max(max,sum)
      }
      rep++
    }
    return max
  }

  if(k===1) return sumMax(k,n)%MOD
  else {
    let max=sumMax(2,n)
    let sumMed=arr.reduce((acc,x)=>acc+x,0)*(k-2)
    return Math.max(max,sumMed+max)%MOD
  }
};