338. Counting Bits

题目描述：给定一个整数n，计算0到n每个数的二进制表示中1的个数

解题思路：可以使用动态规划。一个整数可以看做离它最近的二次幂加上另一个数

重点：2次幂为0,1为1，以此类推

public class Solution {public int[] CountBits(int num) {int[] bits = new int[num + 1];bits[0] = 0;if (num == 0)return bits;bits[1] = 1;if (num == 1)return bits;for (int i = 2; i <= num; i++){int m = (int)Math.Log(i, 2);int closeM = (int)Math.Pow(2, m);if (closeM == i)bits[i] = 1;else{bits[i] = bits[closeM] + bits[i - closeM];}}return bits;}}