Journal Archive

2022

/**
 * @param {number} n
 * @return {number[]}
 */
var countBits = function(n) {
    const dp = [0];
    for (let i = 1; i <= n; i++) {
        if (i % 2 === 0) {
            dp[i] = dp[i/2];
        } else {
            dp[i] = dp[i - 1] + 1;
        }
    }
    return dp;
};

Day 59: Solving one of LeetCode problems

338. Counting Bits Difficulty - Easy

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.

 

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