[LeetCode 217,219][简单]存在重复元素/存在重复元素II

217.存在重复元素
题目链接

class Solution {
public:
    bool containsDuplicate(vector<int>& nums) {
        unordered_set<int>ms;
        for(auto i : nums){
            if(ms.count(i))return true;
            ms.insert(i);
        }
        return false;
    }
};

219.存在重复元素II
题目链接

class Solution {
public:
    bool containsNearbyDuplicate(vector<int>& nums, int k) {
        ios::sync_with_stdio(0);
        unordered_map<int,int>mmp;
        for(int i = 0;i<nums.size();i++){
            if(mmp.find(nums[i])!=mmp.end()){
                if(mmp[nums[i]])return true;
                mmp[nums[i]]++;
            }
            else mmp[nums[i]] = 1;
            if(i>=k)mmp[nums[i-k]]--;
        }
        return false;
    }
};