2206. Divide Array Into Equal Pairs

發表於 | 分類於

problem

solution

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class Solution {
public:
    bool divideArray(vector<int>& nums) {
        unordered_map<int,int> freq;
        for(int n:nums) freq[n]++;
        for(auto m:freq) {
            if(m.second%2==1) return false;
        }
        return true;
        
        
    }
};
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class Solution {
public:
    bool divideArray(vector<int>& nums) {
        vector<int> vec(501,0);
        for(int n:nums) vec[n]++;
        for(int i=1;i<=500;++i){
            if(vec[i]%2==1) return false;
        }
        return true;
    }
};

analysis

  • time complexity O(nlogn)
  • space complexity O(n)