cpp-problems/Leetcode 338.cpp at main · Hritik003/cpp-problems · GitHub

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class Solution {
public:
    vector<int> countBits(int n) {
        vector<int> v;
        for(int i=0;i<=n;++i)
        {
            int c = one_count(i);
            v.push_back(c);
        }
        return {v};

    }
    int one_count(int n)
    {
        int count=0;
        if(n==0)return 0;
        else if(n==1) return 1;
        else
        {
            while(n>0)
           {
                int rem = n%2;
                if(rem==1) count++;
                n=n/2;
             }
        }
        return count;
    }
};


//optimized solution

class Solution {
public:
    vector<int> countBits(int n) {
        vector<int>ans;
        for(int i=0;i<=n;i++){
            int x = __builtin_popcount(i);
            ans.push_back(x);

        }
        return ans;
    }
};