Given an array of integers and an integer k, find out whether there are two distinct indices i and j in the array such that nums[i] = nums[j] and the absolute difference between i and j is at most k.
其实又是水题，跟上一题没变多少，不过这里给了个k，要求数组中相同的element的index之差小于k
public boolean containsDuplicate(int[] nums, int k) {
HashMap<Integer, Integer> hm = new HashMap<>();
int x = 0;
for (int i=0; i<nums.length; i++) {
x = nums[i];
if (hm.containsKey(x)) {
if ((i - hm.get(x)) <= k)
return true;
}
hm.put(x, i);
}
return false;
}要注意的就是跟上题是判断是否存在同个数字不同，这里同个数字的index之差可能有大有小，所以先全存到map里去过一遍，如果有符合的就return true
