Counting Bits Problem & Solution
Given an integer n, return an array ans of length n + 1 such that for each i (0 <= i <= n), ans[i] is the number of 1's in the binary representation of i.
See the counting bits problem on LeetCode.
C++ Solution
#pragma GCC optimize("Ofast")
#pragma GCC optimization("unroll-loops")
static const int _=[](){std::ios::sync_with_stdio(false);cin.tie(nullptr);cout.tie(nullptr);return 0;}();
class Solution {
public:
vector<int> countBits(int n) {
vector<int> results(n + 1, 0);
for (int i = 1; i < results.size(); ++i) {
results[i] = __builtin_popcount(i);
}
return results;
}
};