1 class Solution { 2     public boolean containsDuplicate(int[] nums) { 3         HashMap
     
       m = new HashMap
      
       (); 4         for(int i = 0; i < nums.length; i++) { 5             if (m.containsKey(nums[i])) { 6                 return true; 7             }else { 8                 m.put(nums[i], 1); 9             }10         }11         return false;12     }13 }