1.Two Sum

/*
     * 1.Two Sum
     * 2016-4-8 by Mingyang
     * 注意HashMap的containsKey,put的用法
     */
     public int[] twoSum(int[] nums, int target) {
            int[] res=new int[2];
            if(nums.length==0||nums==null)
              return res;
            HashMap<Integer,Integer> map=new HashMap<Integer,Integer>();
            for(int i=0;i<nums.length;i++){
                if(map.containsKey(nums[i])){
                    res[0]=map.get(nums[i]);
                    res[1]=i;
                }else{
                    int temp=target-nums[i];
                     map.put(temp,i);
                }
            }
            return res;
        }