Adding 125-Valid-Palindrome.c

Author: FahadulShadhin

c/125-Valid-Palindrome.c

@@ -0,0 +1,30 @@
+/*
+    Time: O(n)
+    Space: O(1)
+*/
+
+bool isPalindrome(char * s){
+    int n = strlen(s);
+    if (n==1) return true;
+    
+    int left = 0;
+    int right = n-1;
+    
+    while (left < right) {
+        if (isalnum(s[left]) && isalnum(s[right])) {
+            char leftChar = tolower(s[left]);
+            char rightChar = tolower(s[right]);
+            
+            if (leftChar != rightChar) {
+                return false;
+            }
+            left++;
+            right--;
+        }
+        
+        if (!isalnum(s[left])) left++;
+        if (!isalnum(s[right])) right--;
+    }
+    
+    return true;
+}