LeetCode --- 338. Counting Bits

338. Counting Bits

Difficulty: Medium

Given a non negative integer number num. For every numbers i in the range 0 ≤ i ≤ num calculate the number of 1’s in their binary representation and return them as an array.

Example 1:

Input: 2
Output: [0,1,1]

Example 2:

Input: 5
Output: [0,1,1,2,1,2]

Solution

Language: C++

class Solution {
public:
    vector countBits(int num) {
        vector bits(num+1, 0);
        for (int i = 1; i <= num; i++)
            bits[i] = bits[i & (i-1)] + 1;
        return bits;
    }
};