Add 0929-unique-email-addresses.c

c/0929-unique-email-addresses.c

@@ -0,0 +1,53 @@
+// Represent an element in a hash table.
+typedef struct Hash {
+    char* key;
+    UT_hash_handle hh;
+} Hash;
+
+char *EmailToKey(char *email) {
+    int len = strlen(email);
+    char *key = (char*)malloc( len + 1);
+    char *k = key;
+    int domain = 0;
+    int i;
+
+    for (i = 0; i < len; i++) {
+        if (!domain && email[i] == '.') {
+            continue;
+        }
+        if (email[i] == '+') {
+            while(i < len && email[i] != '@') {
+                i++;
+            }
+        }
+        if (email[i] == '@') {
+            domain = 1;
+        }
+        *k++ = email[i];
+    }
+    *k = '\0';
+
+    return key;
+}
+
+int numUniqueEmails(char ** emails, int emailsSize){
+    Hash *root = NULL;
+    Hash *entry = NULL;
+    char *key = NULL;
+    int i;
+
+    for (i = 0; i < emailsSize; i++) {
+        entry = NULL;
+        key = EmailToKey(emails[i]);
+        HASH_FIND_STR(root, key, entry);
+        if (!entry) {
+            entry = malloc(sizeof(Hash));
+            entry->key = key;
+            HASH_ADD_KEYPTR(hh, root, key, strlen(key), entry);
+        } else {
+            free(key);
+        }
+    }
+
+    return HASH_COUNT(root);
+}