Array Hash Table
Description:
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.
本来继续沿用I里的HashSet，奈何用的不熟，不会用....
用了HashMap，发现网上很多人跟我用的一样，明明是通过不了的，也不知道他们是怎么通过的....
public class Solution {
public boolean containsNearbyDuplicate(int[] nums, int k) {
if (nums.length <= 0)
return false;
Map<Integer, Integer> map = new HashMap<>();
for (int i = 0; i < nums.length; i++) {
if (map.containsKey(nums[i])) {
int j = map.get(nums[i]);
if (i - j <= k)
return true;
} else {
map.put(nums[i], i);
}
}
return false;
}
}
测试用例：[1,0,1,1] 1 无法通过
参考了HashSet方法，设置了一个长度为k的窗口，通过移动窗口来确定是否满足条件，好机智！
public class Solution {
public boolean containsNearbyDuplicate(int[] nums, int k) {
Set<Integer> set = new HashSet<Integer>();
int start = 0, end = 0;
for(int i = 0; i < nums.length; i++) {
if(!set.contains(nums[i])) {
set.add(nums[i]);
end++;
} else {
return true;
}
if(end - start > k) {
set.remove(nums[start]);
start++;
}
}
return false;
}
}