August Coding challenge day4

Author: shrinathjoshi

August Challenge/com/leetcode/AugustChallenge/week1/ValidPalindrome.java

@@ -0,0 +1,39 @@
+package com.leetcode.AugustChallenge.week1;
+
+public class ValidPalindrome {
+	public boolean isPalindrome(String s) {
+
+		String str = preprocessInputString(s);
+
+		int left = 0;
+		int right = str.length() - 1;
+
+		while (left < right) {
+			if (str.charAt(left) != str.charAt(right))
+				return false;
+			left++;
+			right--;
+		}
+		return true;
+	}
+
+	public String preprocessInputString(String s) {
+		int n = s.length();
+		s = s.toLowerCase();
+		String result = "";
+		for (int i = 0; i < n; i++) {
+			char ch = s.charAt(i);
+			if (Character.isLetterOrDigit(ch)) {
+				result += ch;
+			}
+		}
+		return result;
+	}
+
+	public static void main(String[] args) {
+		String s = "A man, a plan, a canal: Panama";
+		System.out.println(new ValidPalindrome().isPalindrome(s));
+
+	}
+
+}