add .c and exemple_collision.c

src/bst.c

+struct node_t {
+  unsigned long int key;
+  void* val;
+  struct node_t* left;
+  struct node_t* right;
+};
+
+typedef struct bst_t {
+  // Use this to compute a key from a val
+  // It is not really a hash function, the key must be unique
+  unsigned long int (*h)(void*);
+
+  unsigned long int size;
+  struct node_t* tree;
+} bst_t;
+
+bst_t bst_empty(void){
+}
+
+int bst_is_empty(bst_t t){
+}
+
+bst_t bst_add(bst_t t, void* x){
+}
+
+void bst_destroy(bst_t t, void (*free_void)(void*)){
+}
+
+int bst_in(bst_t t, void* x){
+}
+
+unsigned long int bst_size(bst_t t){
+}

src/hash_tbl.c

+#include <stddef.h>
+#include "list.h"
+
+#define ARRAY_CAPACITY 1 << 16
+
+struct hash_tbl {
+  size_t (*h)(void*);
+  int (*eq)(void*, void*);
+  void (*free)(void*);
+  unsigned long int size;
+  size_t capacity; // array length
+  list_t* array;
+};
+
+typedef struct hash_tbl* hash_tbl;
+
+hash_tbl htbl_empty(size_t (*h)(void*),
+                    int (*eq)(void*, void*),
+                    void (*free)(void*)){
+}
+
+int htbl_add(hash_tbl htbl, void* x){
+}
+
+int htbl_in(hash_tbl htbl, void* x){
+}
+
+void htbl_destroy(hash_tbl htbl){
+}
+  

src/list.c

+struct cell_t {
+  void* val;
+  unsigned long int id;
+  struct cell_t* next;
+};
+
+typedef struct cell_t* list_t;
+
+list_t list_empty(){
+}
+
+int list_is_empty(list_t l){
+}
+
+list_t list_push(list_t l, void* x){
+}
+
+list_t list_tail(list_t l){
+}
+
+void* list_pop(list_t* l){ 
+}
+
+void* list_top(list_t l){
+}
+
+void list_destroy(list_t l, void (*free)(void*)){
+}
+
+// return the found element or NULL
+void* list_in(list_t l, void* x, int (*eq)(void*, void*)){
+}
+
+unsigned long int list_len(list_t l){
+}
+

src/linked_list.h → src/list.h

@@ -16,7 +16,7 @@ list_t list_tail(list_t);
 void* list_pop(list_t*);
 void* list_top(list_t);
 void list_destroy(list_t, void (*free)(void*));
-int list_in(list_t, void*, int (*eq)(void*, void*));
+void* list_in(list_t, void*, int (*eq)(void*, void*));
 unsigned long int list_len(list_t);
 
 #endif

tests/exemple_collision.c

+#include <stdlib.h>
+#include <stdio.h>
+#include <time.h>
+#include <openssl/md5.h>
+#include "list.h"
+
+typedef struct pair_t {
+  char x[8];
+  unsigned char h;
+}* pair_t;
+
+int eq_pair(void* a, void* b){
+  return ((pair_t)a)->h == ((pair_t)b)->h;
+}
+
+/* char x[8] */
+unsigned char md5_first_byte(const char* x){
+  unsigned char digest[MD5_DIGEST_LENGTH];
+  
+  MD5((const unsigned char*)x, 8, digest);
+  return digest[0]; // we keep only the first byte
+}
+
+int main(){
+  pair_t p, q;
+  list_t l;
+  unsigned int i = 0;
+
+  srand(time(NULL));
+
+  l = list_empty();
+  
+  for(;;){
+    p = (pair_t)malloc(sizeof(struct pair_t));
+    for(int i = 0; i < 7; i++)
+      p->x[i] = rand() % (126-32-1) + 32;
+    p->x[7] = 0;
+    p->h = md5_first_byte(p->x);
+
+    if((q = (pair_t)list_in(l, p, eq_pair)) != NULL){
+      printf("After %d iterations, a collision happened !\n", i);
+      printf("%s and %s have the same MD5 first byte.\n", p->x, q->x);
+
+      return 0;
+    } else {
+      l = list_push(l, p);
+    }
+  }
+}
+