Maximum Sum Subarray of Size K in Java: Explanation & Practice

Find maximum sum of any contiguous subarray of size k

Problem summary

Given an array and integer k, find the maximum sum of any contiguous subarray of size k. Use sliding window for O(n) solution.

Starter code

public class Main {
    public static void main(String[] args) {
        int[] nums = {2, 1, 5, 1, 3, 2};
        int k = 3;
        
        // Sliding window: maintain sum of k elements
        // Slide by adding new element and removing old
        // Print: Max sum: 9
    }
}

Expected output and test cases

[2,1,5,1,3,2], k=3 → 5+1+3
```
Max sum: 9
```
[2,3,4,1,5], k=2 → 3+4
```
Max sum: 7
```
[1,2,3,4,5], k=5 → all
```
Max sum: 15
```

Hints

First compute sum of first k elements
Then slide: add nums[i], subtract nums[i-k]
Track maximum sum seen
This avoids recomputing sum from scratch each time

Related Data Structures & Algorithms exercises

Practice all Data Structures & Algorithms exercises · Run this idea in the Java compiler