图片说明 

class Solution {
   public int[] twoSum(int[] numbers, int target) {
        int flag[] = new int [2];
        int l = 0 ;
        int r = numbers.length-1;
        while(l<r) {
            if((numbers[l]+ numbers[r])<target) {
                l++;
            }
            else if((numbers[l]+numbers[r])>target) {
                r--;
            }
            else {
                flag[0] = l+1;
                flag[1] = r+1;
                break;
            }
        }
        return flag;
    }
}

还可用hash表

 public int[] twoSum(int[] numbers, int target) {
        int flag[] = new int [2];
        HashMap<Integer,Integer> hm = new HashMap<Integer,Integer>();
        for(int i = 0 ; i < numbers.length; i++) {
            if(hm.containsKey(target-numbers[i])) {
                flag[0] = hm.get(target-numbers[i])+1;
                flag[1] = i+1;
                break;
            }
            else{
                hm.put(numbers[i],i);
            }
        }
        return flag;
    }
}