Minimum Sum of Mountain Triplets I

export function minimumSum(nums: number[]): number {
  const n = nums.length;
  const left = [...nums];
  const right = [...nums];
  for (let i = 1; i < n; i++) {
    left[i] = Math.min(left[i], left[i - 1]);
  }
  for (let i = n - 2; 0 <= i; i--) {
    right[i] = Math.min(right[i], right[i + 1]);
  }
 
  let answer = Number.MAX_SAFE_INTEGER;
  for (let i = 1; i < n - 1; i++) {
    if (left[i - 1] < nums[i] && nums[i] > right[i + 1]) {
      answer = Math.min(answer, nums[i] + left[i - 1] + right[i + 1]);
    }
  }
  return answer === Number.MAX_SAFE_INTEGER ? -1 : answer;
}