2908. Minimum Sum of Mountain Triplets I LeetCode Solution

In this guide, you will get 2908. Minimum Sum of Mountain Triplets I LeetCode Solution with the best time and space complexity. The solution to Minimum Sum of Mountain Triplets I problem is provided in various programming languages like C++, Java, and Python. This will be helpful for you if you are preparing for placements, hackathons, interviews, or practice purposes. The solutions provided here are very easy to follow and include detailed explanations.

Problem Statement
Complexity Analysis
Minimum Sum of Mountain Triplets I solution in C++
Minimum Sum of Mountain Triplets I solution in Java
Minimum Sum of Mountain Triplets I solution in Python
Additional Resources

2908. Minimum Sum of Mountain Triplets I LeetCode Solution image

Problem Statement of Minimum Sum of Mountain Triplets I

You are given a 0-indexed array nums of integers.
A triplet of indices (i, j, k) is a mountain if:

i < j < k
nums[i] < nums[j] and nums[k] < nums[j]

Return the minimum possible sum of a mountain triplet of nums. If no such triplet exists, return -1.

Example 1:

Input: nums = [8,6,1,5,3]
Output: 9
Explanation: Triplet (2, 3, 4) is a mountain triplet of sum 9 since:
– 2 < 3 < 4
– nums[2] < nums[3] and nums[4] < nums[3]
And the sum of this triplet is nums[2] + nums[3] + nums[4] = 9. It can be shown that there are no mountain triplets with a sum of less than 9.

Example 2:

Input: nums = [5,4,8,7,10,2]
Output: 13
Explanation: Triplet (1, 3, 5) is a mountain triplet of sum 13 since:
– 1 < 3 < 5
– nums[1] < nums[3] and nums[5] < nums[3]
And the sum of this triplet is nums[1] + nums[3] + nums[5] = 13. It can be shown that there are no mountain triplets with a sum of less than 13.

Example 3:

Input: nums = [6,5,4,3,4,5]
Output: -1
Explanation: It can be shown that there are no mountain triplets in nums.

Constraints:

3 <= nums.length <= 50
1 <= nums[i] <= 50

Complexity Analysis

Time Complexity: O(n)
Space Complexity: O(n)

2908. Minimum Sum of Mountain Triplets I LeetCode Solution in C++

class Solution {
 public:
  int minimumSum(vector<int>& nums) {
    const int n = nums.size();
    int ans = INT_MAX;
    vector<int> minPrefix(n);
    vector<int> minSuffix(n);

    partial_sum(nums.begin(), nums.end(), minPrefix.begin(),
                [](int x, int y) { return min(x, y); });
    partial_sum(nums.rbegin(), nums.rend(), minSuffix.begin(),
                [](int x, int y) { return min(x, y); });
    ranges::reverse(minSuffix);

    for (int i = 0; i < n; ++i)
      if (nums[i] > minPrefix[i] && nums[i] > minSuffix[i])
        ans = min(ans, nums[i] + minPrefix[i] + minSuffix[i]);

    return ans == INT_MAX ? -1 : ans;
  }
};
/* code provided by PROGIEZ */

2908. Minimum Sum of Mountain Triplets I LeetCode Solution in Java

class Solution {
  public int minimumSum(int[] nums) {
    final int n = nums.length;
    int ans = Integer.MAX_VALUE;
    int[] minPrefix = new int[n];
    int[] minSuffix = new int[n];

    minPrefix[0] = nums[0];
    minSuffix[n - 1] = nums[n - 1];

    for (int i = 1; i < n; ++i)
      minPrefix[i] = Math.min(minPrefix[i - 1], nums[i]);

    for (int i = n - 2; i >= 0; --i)
      minSuffix[i] = Math.min(minSuffix[i + 1], nums[i]);

    for (int i = 0; i < n; ++i)
      if (nums[i] > minPrefix[i] && nums[i] > minSuffix[i])
        ans = Math.min(ans, nums[i] + minPrefix[i] + minSuffix[i]);

    return ans == Integer.MAX_VALUE ? -1 : ans;
  }
}
// code provided by PROGIEZ

2908. Minimum Sum of Mountain Triplets I LeetCode Solution in Python

class Solution:
  # Same as 2908. Minimum Sum of Mountain Triplets I
  def minimumSum(self, nums: list[int]) -> int:
    ans = math.inf
    minPrefix = list(itertools.accumulate(nums, min))
    minSuffix = list(itertools.accumulate(reversed(nums), min))[::-1]

    for i, num in enumerate(nums):
      if num > minPrefix[i] and num > minSuffix[i]:
        ans = min(ans, num + minPrefix[i] + minSuffix[i])

    return -1 if ans == math.inf else ans
 # code by PROGIEZ