Maximum subarray (Kadane) in C: solved exercise

If you are looking for maximum subarray (kadane) in c: solved exercise, here is a practical, compilable example focused on the reusable idea behind the exercise.

Problem statement

Compute the maximum contiguous subarray sum in {-2,1,-3,4,-1,2,1,-5,4}.

C solution

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#include <stdio.h>

int kadane(const int a[], int n) {
    int mejor = a[0];
    int actual = a[0];

    for (int i = 1; i < n; i++) {
        actual = (actual + a[i] > a[i]) ? actual + a[i] : a[i];
        mejor = (mejor > actual) ? mejor : actual;
    }
    return mejor;
}

int main(void) {
    int a[] = {-2, 1, -3, 4, -1, 2, 1, -5, 4};
    printf("%d\n", kadane(a, 9));
    return 0;
}

Expected output

1
6

Common mistakes

Not testing edge cases such as small or empty inputs.
Not validating indices, pointers, or limits carefully enough.
Copying the mechanics without understanding the general pattern.

Practical use

The key idea is to identify a reusable pattern instead of stopping at “it works once”.

Recommended next exercise

Guided practice and full book

If you want a complete path with progressive difficulty:

FAQ

Is this exercise useful in practice?

Yes. It is designed to teach a reusable C pattern rather than a one-off toy example.

How should I practice it better?

Change the input data, add edge cases, and rewrite it from scratch without looking at the solution.

How should I practice this exercise type to improve faster?

Start with small inputs, run edge cases (empty, one item, max capacity), then rewrite the solution from scratch without copying.