Find the middle node in a linked list.

ll-find-middle-node.c

//
//  File.c
//  
//
//  Created by Kenneth Ballenegger on 1/13/14.
//
//

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


typedef struct node_t *node_p;
typedef struct node_t {
    int value;
    node_p next;
} node_t;

node_p new_node(int value, node_p next) {
    node_p node = calloc(1, sizeof(node));
    node->value = value;
    return node;
}

// i'm leaking memory, i don't care. fuck it

int middle_node_int(node_p node) {
    node_p middle_node = NULL;
    middle_node_int_rec(node, 0, &middle_node);
    return middle_node->value;
    
}

// note: does not account for lists with an even number of node, handled by int division
// used internally only, returns max
int middle_node_int_rec(node_p next, int count_so_far, node_p *output) {
    if (next->next) {
        int max = middle_node_int_rec(next->next, count_so_far + 1, output);
        if (count_so_far == max / 2) {
            *output = next;
        }
        return max;
    } else {
        return count_so_far;
    }
}


int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */
    
    // creating nodes, from last to first
    node_p node;
    node = new_node(9, NULL);
    node = new_node(8, node);
    node = new_node(7, node);
    node = new_node(6, node);
    node = new_node(5, node);
    node = new_node(4, node);
    node = new_node(3, node);
    node = new_node(2, node);
    node = new_node(1, node);
    
    return middle_node_int(node);
}