Contains DuplicateII

超时版：

/*Contains Duplicate II
Given an array of integers and an integer k, find out whether there there are two distinct indices i and j in the array such that nums[i] = nums[j] and the difference between i and j is at most k.
*/

public class Leetcode2 {

    public static void main(String[] args) {
        int arr[]= {1,2,34,43,1};
        System.out.println(containsNearbyDuplicate(arr,1));

        // TODO Auto-generated method stub

    }

        public static boolean containsNearbyDuplicate(int[] nums, int k) {

                for (int i = 0; i < nums.length - 1; i++) {
                    int temp = k + i;
                    int y = ((temp > nums.length - 1) ? nums.length : temp+1);
                    for (int j = 1; j < y; j++) {
                        int x = ((i+j )> nums.length - 1) ? nums.length-1 : (i+j);
                        if((nums[x] - nums[i])==0)
                            return true;
                    }
                }
                return false;
            }

    /* public static boolean containsNearbyDuplicate(int[] nums, int k) {

         int x;
         for (int i = 0; i < nums.length - 1; i++) {
        int temp = k + i;

     while(temp<=nums.length-1)
     {   int temp2=temp;
     for(int j=i+1;j<temp2;j++) {
         x=nums[j]-nums[i];
         if(x==0)
             return true;
     }
     }

    }
             return false;
     }
*/

}

AC版：注意集合框架的使用！！

public class Solution {
    public boolean containsNearbyDuplicate(int[] nums, int k) {

		Map<Integer,Integer> tm=new TreeMap<Integer,Integer>();

			{
				for (int i = 0; i < nums.length ; i++)
				{

				if(tm.containsKey(nums[i]))
				  {
					int j=tm.get(nums[i]);
					if((i-j)<=k)
				 	return true;
				  }
				tm.put(nums[i],i);
			    }
				return false;
			}	

}
}