leetcode02

Input: 121
Output: true

Input: -121
Output: false
Explanation: From left to right, it reads -121. From right to left, it becomes 121-. Therefore it is not a palindrome.

Input: 10
Output: false
Explanation: Reads 01 from right to left. Therefore it is not a palindrome.

class Solution {
    public boolean isPalindrome(int x) {
        if (x < 0) {
            return false;
        }

        List<Integer> digitals = getNumbers(x);
        int count = digitals.size();
        for (int i = 0; i < count / 2; i++) {
            if (digitals.get(i) != digitals.get(count - 1 - i)) {
                return false;
            }
        }

        return true;
    }

    private List<Integer> getNumbers(int x) {
        List<Integer> digitals = new ArrayList<Integer>();
        long y = (long)x;
        for (;y > 0;) {
            int z = (int) (y % 10);
            digitals.add(z);
            y = y / 10;
        }

        return digitals;
    }
}

class Solution {
    public int romanToInt(String s) {
     int num = 0;
     char[] chars = s.toCharArray();

     for (int i = 0; i < chars.length; ) {
         char cur = chars[i];

            switch (cur) {
           case 'I':
                if (i == chars.length - 1) {
                 num += 1;
                    i++;
             } else {
                 char next = chars[i + 1];
                    if (next == 'V') {
                       num += 4;
                        i += 2;
                  } else if (next == 'X') {
                        num += 9;
                        i += 2;
                  } else {
                     num += 1;
                        i++;
                 }
                }
                break;
           case 'X':
                if (i == chars.length - 1) {
                 num += 10;
                   i++;
             } else {
                 char next = chars[i + 1];
                    if (next == 'L') {
                       num += 40;
                       i += 2;
                  } else if (next == 'C') {
                        num += 90;
                       i += 2;
                  } else {
                     num += 10;
                       i++;
                 }
                }
                break;
           case 'C':
                if (i == chars.length - 1) {
                 num += 100;
                  i++;
             } else {
                 char next = chars[i + 1];
                    if (next == 'D') {
                       num += 400;
                      i += 2;
                  } else if (next == 'M') {
                        num += 900;
                      i += 2;
                  } else {
                     num += 100;
                      i++;
                 }
                }
                break;

          case 'V':
                num += 5;
                i++;
             break;
           case 'L':
                num += 50;
               i++;
             break;
           case 'D':
                num += 500;
              i++;
             break;
           case 'M':
                num += 1000;
             i++;
         }
        }

       return num;
  }
}