167.Two Sum II-Input array is sorted

     /*
      * 167.Two Sum II-Input array is sorted
      * 2016-6-4 by Mingyang
      * Given an array of integers that is already sorted in ascending order, 
      * find two numbers such that they add up to a specific target number.
      *The function twoSum should return indices of the two numbers such that they add up to the target, 
      *where index1 must be less than index2. 
      *Please note that your returned answers (both index1 and index2) are not zero-based.
      */
      public int[] twoSum(int[] numbers, int target) {  
            if(numbers==null || numbers.length < 1) return null;  
            int i=0, j=numbers.length-1;  
              
            while(i<j) {  
                int x = numbers[i] + numbers[j];  
                if(x<target) {  
                    ++i;  
                } else if(x>target) {  
                    --j;  
                } else {  
                    return new int[]{i+1, j+1};  
                }  
            }  
            return null;  
        }