1031-maximum-sum-of-two-non-overlapping-subarrays.js

/**
 * @param {number[]} A
 * @param {number} L
 * @param {number} M
 * @return {number}
 */
const maxSumTwoNoOverlap = function(A, L, M) {
  for(let i = 1, len = A.length; i < len; i++) {
    A[i] += A[i - 1]
  }
  let LMax = A[L - 1], MMax = A[M - 1], res = A[L + M - 1]
  for(let i = L + M, len = A.length; i < len; i++) {
    LMax = Math.max(LMax, A[i - M] - A[i - M - L])
    MMax = Math.max(MMax, A[i - L] - A[i - M - L])
    res = Math.max(res, Math.max(LMax + A[i] - A[i - M], MMax + A[i] - A[i - L]))
  }
  return res
}

// another

const maxSumTwoNoOverlap = function(A, L, M) {
  let n = A.length
  let sum = []
  sum[0] = 0
  for (let i = 0; i < n; i++) sum[i + 1] = sum[i] + A[i]

  let ans = 0
  for (let i = L - 1; i + M < n; ++i) {
    for (let j = i + 1; j + M - 1 < n; ++j) {
      ans = Math.max(ans, sum[i + 1] - sum[i - L + 1] + sum[j + M] - sum[j])
    }
  }
  let tmp = L
  L = M
  M = tmp
  for (let i = L - 1; i + M < n; ++i) {
    for (let j = i + 1; j + M - 1 < n; ++j) {
      ans = Math.max(ans, sum[i + 1] - sum[i - L + 1] + sum[j + M] - sum[j])
    }
  }
  return ans
}