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 numsi = numsj and the difference between i and j is at most k.
建立一个map，key是出现过的元素，value是该元素的下标。若相同元素距离大于k，则更新下标。
代码语言：txt复制 public boolean containsNearbyDuplicate(int[] nums, int k) {
Map<Integer, Integer> map = new HashMap<Integer, Integer>();
for (int i = 0; i < nums.length; i ) {
if (map.containsKey(nums[i])) {
if (i - map.get(nums[i]) <= k) {
return true;
}
}
map.put(nums[i], i);
}
return false;
}
