Given an input array of integers and a positive integer k, find out the maximum sum of a contiguous subarray of length exactly k
Example
Input: nums = [5, 6, 1, 2, 6, 6, 4, 3], k = 3
Output: 4 6
Explanation: The subarray nums[4...6] has the maximum sum of 16
The core challenge of this problem is to find the maximum sum of any contiguous subarray of length k. This problem is significant in various applications such as financial analysis, where one might want to find the period with the highest profit.
Potential pitfalls include misunderstanding the requirement for the subarray to be contiguous and not considering edge cases where the array length is less than k.
To solve this problem, we can use a sliding window approach. The sliding window technique is optimal for problems involving contiguous subarrays or substrings.
1. **Naive Solution**: Calculate the sum of every possible subarray of length k and keep track of the maximum sum. This approach has a time complexity of O(n*k), which is not efficient for large arrays.
2. **Optimized Solution**: Use the sliding window technique to maintain a running sum of the current window of length k. Slide the window one element at a time, updating the sum by subtracting the element that is left behind and adding the new element. This approach has a time complexity of O(n).
1. Initialize the sum of the first window of length k.
2. Slide the window from the start of the array to the end, updating the sum by subtracting the element that is left behind and adding the new element.
3. Keep track of the maximum sum encountered during this process.
// Function to find the maximum sum of a subarray of length k
function maxSumSubarray(nums, k) {
// Edge case: if the array length is less than k
if (nums.length < k) {
return null;
}
// Initialize the sum of the first window
let maxSum = 0;
for (let i = 0; i < k; i++) {
maxSum += nums[i];
}
// Initialize the current sum to the maxSum
let currentSum = maxSum;
// Slide the window over the array
for (let i = k; i < nums.length; i++) {
// Update the current sum by subtracting the element that is left behind
// and adding the new element
currentSum += nums[i] - nums[i - k];
// Update the maxSum if the current sum is greater
maxSum = Math.max(maxSum, currentSum);
}
return maxSum;
}
// Example usage
const nums = [5, 6, 1, 2, 6, 6, 4, 3];
const k = 3;
console.log(maxSumSubarray(nums, k)); // Output: 16
The time complexity of the sliding window approach is O(n) because we traverse the array only once. The space complexity is O(1) as we are using a constant amount of extra space.
1. If the array length is less than k, the function should return null.
2. If all elements are negative, the function should still return the maximum sum, which could be a negative number.
To test the solution comprehensively, consider the following test cases:
When approaching such problems, it is crucial to understand the requirements and constraints. Breaking down the problem and considering different approaches can help in finding the optimal solution. Practicing similar problems and studying algorithms like the sliding window technique can improve problem-solving skills.
In this blog post, we discussed the problem of finding the maximum sum of a contiguous subarray of length k. We explored a naive solution and an optimized sliding window approach. Understanding and solving such problems is essential for improving algorithmic thinking and coding skills.