Counting Bits
Problem Statement - link #
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.
Examples #
Example 1:
Input: n = 2
Output: [0,1,1]
Explanation:
0 --> 0
1 --> 1
2 --> 10
Example 2:
Input: n = 5
Output: [0,1,1,2,1,2]
Explanation:
0 --> 0
1 --> 1
2 --> 10
3 --> 11
4 --> 100
5 --> 101
Constraints #
0 <= n <= 10^5
Solutions #
class Solution {
public:
int bits(int i){
int res=0;
while(i>0){
i = (i & (i-1));
res++;
}
return res;
}
vector<int> countBits(int n) {
vector<int> ans(n+1);
for(int i=0; i<=n; i++){
ans[i]=bits(i);
}
return ans;
}
};