918. Maximum Sum Circular Subarray LeetCode Solution

Last updated: February 21, 2025

In this guide, you will get 918. Maximum Sum Circular Subarray LeetCode Solution with the best time and space complexity. The solution to Maximum Sum Circular Subarray 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
Maximum Sum Circular Subarray solution in C++
Maximum Sum Circular Subarray solution in Java
Maximum Sum Circular Subarray solution in Python
Additional Resources

918. Maximum Sum Circular Subarray LeetCode Solution image

Problem Statement of Maximum Sum Circular Subarray

Given a circular integer array nums of length n, return the maximum possible sum of a non-empty subarray of nums.
A circular array means the end of the array connects to the beginning of the array. Formally, the next element of nums[i] is nums[(i + 1) % n] and the previous element of nums[i] is nums[(i – 1 + n) % n].
A subarray may only include each element of the fixed buffer nums at most once. Formally, for a subarray nums[i], nums[i + 1], …, nums[j], there does not exist i <= k1, k2 <= j with k1 % n == k2 % n.

Example 1:

Input: nums = [1,-2,3,-2]
Output: 3
Explanation: Subarray [3] has maximum sum 3.

Example 2:

Input: nums = [5,-3,5]
Output: 10
Explanation: Subarray [5,5] has maximum sum 5 + 5 = 10.

Example 3:

Input: nums = [-3,-2,-3]
Output: -2
Explanation: Subarray [-2] has maximum sum -2.

Constraints:

n == nums.length
1 <= n <= 3 * 104
-3 * 104 <= nums[i] <= 3 * 104

Complexity Analysis

Time Complexity:
Space Complexity:

918. Maximum Sum Circular Subarray LeetCode Solution in C++

class Solution {
 public:
  int maxSubarraySumCircular(vector<int>& nums) {
    int totalSum = 0;
    int currMaxSum = 0;
    int currMinSum = 0;
    int maxSum = INT_MIN;
    int minSum = INT_MAX;

    for (const int num : nums) {
      totalSum += num;
      currMaxSum = max(currMaxSum + num, num);
      currMinSum = min(currMinSum + num, num);
      maxSum = max(maxSum, currMaxSum);
      minSum = min(minSum, currMinSum);
    }

    return maxSum < 0 ? maxSum : max(maxSum, totalSum - minSum);
  }
};
/* code provided by PROGIEZ */

918. Maximum Sum Circular Subarray LeetCode Solution in Java

class Solution {
  public int maxSubarraySumCircular(int[] nums) {
    int totalSum = 0;
    int currMaxSum = 0;
    int currMinSum = 0;
    int maxSum = Integer.MIN_VALUE;
    int minSum = Integer.MAX_VALUE;

    for (final int num : nums) {
      totalSum += num;
      currMaxSum = Math.max(currMaxSum + num, num);
      currMinSum = Math.min(currMinSum + num, num);
      maxSum = Math.max(maxSum, currMaxSum);
      minSum = Math.min(minSum, currMinSum);
    }

    return maxSum < 0 ? maxSum : Math.max(maxSum, totalSum - minSum);
  }
}
// code provided by PROGIEZ

918. Maximum Sum Circular Subarray LeetCode Solution in Python

class Solution:
  def maxSubarraySumCircular(self, nums: list[int]) -> int:
    totalSum = 0
    currMaxSum = 0
    currMinSum = 0
    maxSum = -math.inf
    minSum = math.inf

    for num in nums:
      totalSum += num
      currMaxSum = max(currMaxSum + num, num)
      currMinSum = min(currMinSum + num, num)
      maxSum = max(maxSum, currMaxSum)
      minSum = min(minSum, currMinSum)

    return maxSum if maxSum < 0 else max(maxSum, totalSum - minSum)
 # code by PROGIEZ

Additional Resources

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