adds C valid palindrome

Author: 7astro7

C/strings/test_valid_palindrome.c

@@ -0,0 +1,101 @@
+#include <criterion/criterion.h>
+#include <stdbool.h>
+#include <ctype.h>
+#include <string.h>
+
+/*
+Given a string s, determine if it is a palindrome, considering only 
+alphanumeric characters and ignoring cases.
+Example 1:
+Input: s = "A man, a plan, a canal: Panama"
+Output: true
+Explanation: "amanaplanacanalpanama" is a palindrome.
+Example 2:
+Input: s = "race a car"
+Output: false
+Explanation: "raceacar" is not a palindrome.
+Constraints:
+    1 <= s.length <= 2 * 105
+    s consists only of printable ASCII characters.
+*/
+
+bool 
+is_palindrome(char * s)
+{
+    bool alnum = false;
+    int n = strlen(s);
+    char simplified[n];
+    int i, j = 0;
+    for (i = 0; i < n; i++)
+    {
+        alnum = isalnum(s[i]);
+        if (alnum)
+        {
+            simplified[j++] = tolower(s[i]);
+        }
+    }
+    int new_n = j;
+    i = 0;
+    while (1)
+    {
+        if (i >= new_n)
+        {
+            return true;
+        }
+        if (simplified[i++] != simplified[j - i])
+        {
+            return false;
+        }
+    }
+}
+
+Test(test_valid_palindrome, one_char_returns_true)
+{
+    cr_assert(is_palindrome("G"));
+}
+
+Test(test_valid_palindrome, panama_canal_returns_true)
+{
+    cr_assert(is_palindrome("A man, a plan, a canal: Panama"));
+}
+
+Test(test_valid_palindrome, salmon_returns_false)
+{
+    cr_assert(!is_palindrome("SALMON"));
+}
+
+Test(test_valid_palindrome, hannah_returns_true)
+{
+      cr_assert(is_palindrome("Hannah"));
+}
+
+Test(test_valid_palindrome, matrix_returns_false)
+{
+      cr_assert(!is_palindrome("matrix"));
+}
+
+Test(test_valid_palindrome, 90509_returns_true)
+{
+      cr_assert(is_palindrome("90509"));
+}
+
+Test(test_valid_palindrome, madam_im_adam_returns_true)
+{
+      cr_assert(is_palindrome("Madam I'm Adam"));
+}
+
+Test(test_valid_palindrome, greek_thing_returns_true)
+{
+      cr_assert(is_palindrome("ΝΙΨΟΝ ΑΝΟΜΗΜΑΤΑ ΜΗ ΜΟΝΑΝ ΟΨΙΝ"));
+}
+
+Test(test_valid_palindrome, mr_owl_returns_true)
+{
+      cr_assert(is_palindrome("Mr. Owl ate my metal worm"));
+}
+
+Test(test_valid_palindrome, mr_bowl_returns_false)
+{
+      cr_assert(!is_palindrome("Mr. Bowl ate my metal worm"));
+}
+