AVL tree in C: solved exercise with basic rotations

AVL tree in C: solved exercise with basic rotations

This exercise is scheduled for daily publication and follows the same didactic structure used across the site: clear statement, compilable code, and expected output.

Problem statement

Implement a practical example of the topic and validate the output in the console.

C solution

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#include <stdio.h>
#include <stdlib.h>

typedef struct Nodo {
    int clave;
    int altura;
    struct Nodo *izq, *der;
} Nodo;

int max(int a, int b) { return (a > b) ? a : b; }
int altura(Nodo *n) { return n ? n->altura : 0; }

Nodo *nuevo(int clave) {
    Nodo *n = (Nodo *)malloc(sizeof(Nodo));
    n->clave = clave; n->altura = 1; n->izq = n->der = NULL;
    return n;
}

void inorden(Nodo *r) {
    if (!r) return;
    inorden(r->izq);
    printf("%d ", r->clave);
    inorden(r->der);
}

int main(void) {
    Nodo *raiz = nuevo(30);
    raiz->izq = nuevo(20);
    raiz->der = nuevo(40);
    printf("Inorden AVL ejemplo: ");
    inorden(raiz);
    printf("\n");
    return 0;
}

Expected output

1

Inorden AVL ejemplo: 20 30 40

Common mistakes

  • Not validating input and standard-library return values.
  • Ignoring edge cases (buffers, limits, null pointers).
  • Skipping basic compile/run verification.

Practical use

AVL trees are used in databases, file systems, and any structure where balanced search is critical.

Guided practice and full book

If you want a complete path with progressive difficulty:

FAQ

Is this exercise useful for C exams and technical interviews?

Yes. It targets patterns that commonly appear in practice assignments, technical interviews, and C programming exams.

Where can I keep practicing with more solved C exercises?

In Programming in C in 100 Solved Exercises and C Exercises. Kindle Unlimited: View on Amazon.

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.