Day_14

## 重复的DNA序列

class Solution {
    public List<String> findRepeatedDnaSequences(String s) {

        List<String> ans = new ArrayList<>();

        int n = s.length();

        Map<String , Integer> map = new HashMap<>();

        for(int i = 0 ; i + 10 <= n ; i++){
            String cur = s.substring(i , i + 10);

            int cnt = map.getOrDefault(cur ,0);
            if(cnt == 1) ans.add(cur);
            map.put(cur , cnt + 1);
        }
        return ans;
    }
}

## 存在重复元素2

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

        HashSet<Integer> set = new HashSet<>();

        for(int i = 0 ; i < nums.length ; i++){
            if(set.contains(nums[i])){
                return true;
            }
            set.add(nums[i]);

            if(set.size() > k){
                set.remove(nums[i - k]);
            }
        }
        return false;


    }
}