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-rw-r--r--valid_palindrome.c35
-rw-r--r--valid_palindrome.py35
2 files changed, 70 insertions, 0 deletions
diff --git a/valid_palindrome.c b/valid_palindrome.c
new file mode 100644
index 0000000..d3dfe81
--- /dev/null
+++ b/valid_palindrome.c
@@ -0,0 +1,35 @@
+// 125. Valid Palindrome
+#include "leetcode.h"
+
+/*
+ * a phrase is a palindrome if, after converting all uppercase letters into
+ * lowercase letters, and removing all non-alphanumeric characters, it reads the
+ * same forward and backward. alphanumeric characters include only letters and
+ * numbers. given a string 's', return true if it is a palindrome, or false
+ * otherwise.
+ */
+
+bool isPalindrome(char *s) {
+ int l = 0, r = strlen(s) - 1;
+ while (l < r) {
+ if (isalnum(s[l])) {
+ if (isalnum(s[r])) {
+ if (tolower(s[l]) != tolower(s[r]))
+ return false;
+ l++, r--;
+ } else
+ r--;
+ } else
+ l++;
+ }
+ return true;
+}
+
+int main() {
+ char *s1 = "A man, a plan, a canal: Panama";
+ char *s2 = "race a car";
+ char *s3 = " ";
+ printf("%d\n", isPalindrome(s1)); // expect: 1
+ printf("%d\n", isPalindrome(s2)); // expect: 0
+ printf("%d\n", isPalindrome(s3)); // expect: 1
+}
diff --git a/valid_palindrome.py b/valid_palindrome.py
new file mode 100644
index 0000000..2b361e0
--- /dev/null
+++ b/valid_palindrome.py
@@ -0,0 +1,35 @@
+# 125. Valid Palindrome
+
+"""
+a phrase is a palindrome if, after converting all uppercase letters into
+lowercase letters, and removing all non-alphanumeric characters, it reads the
+same forward and backward. alphanumeric characters include only letters and
+numbers. given a string 's', return true if it is a palindrome, or false
+otherwise.
+"""
+
+
+class Solution(object):
+ def isPalindrome(self, s):
+ """
+ :type s: str
+ :rtype: bool
+ """
+ l, r = 0, len(s) - 1
+ while l < r:
+ while l < r and not s[l].isalnum():
+ l += 1
+ while l < r and not s[r].isalnum():
+ r -= 1
+ if s[l].lower() != s[r].lower():
+ return False
+ l += 1
+ r -= 1
+ return True
+
+
+if __name__ == "__main__":
+ obj = Solution()
+ print(obj.isPalindrome(s="A man, a plan, a canal: Panama"))
+ print(obj.isPalindrome(s="race a car"))
+ print(obj.isPalindrome(s=" "))