public class Solution {
    /*
     * @param chars: The letter array you should sort by Case
     * @return: nothing
     */
    public void sortLetters(char[] chars) {
        // write your code here
        int left = 0;  
        int right = chars.length - 1;  
        while (left < right) {  
            while (left < right && chars[left] >= 'a' && chars[left] <= 'z')  
                left++;  
            while (left < right && chars[right] >= 'A' && chars[right] <= 'Z')  
                right--;  
            if (left < right) {  
                char temp = chars[left];  
                chars[left] = chars[right];  
                chars[right] = temp;  
                left++;  
                right--;  
            }  
        } 
    }
}
add 49