I’m trying to make a DTC in C. This is the structure of the nodes:

typedef struct node{

    int value;
    struct node *lower;
    struct node *higher;

}node;

To free the memory allocated using malloc(), I’ve implemented this function:

void free_nodes(node*a){

    if(a-> higher !=  NULL){
        free_nodes(a-> higher);
    }

    if(a-> lower !=  NULL){
        free_nodes(a-> lower);
    }
        if(a-> higher ==  NULL && a -> lower == NULL){
        free(a);
    }
        
}

It takes the pointer to the root node as a parameter.

I tried to use recursion here but it does not seem to free all the nodes. It is only able to free two nodes (i checked using valgrind)