标签:vector int number num Input Output Counting Bits Leetcode
https://leetcode.com/problems/counting-bits/
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]
Follow up:
- It is very easy to come up with a solution with run time O(n*sizeof(integer)). But can you do it in linear time O(n) /possibly in a single pass?
- Space complexity should be O(n).
- Can you do it like a boss? Do it without using any builtin function like __builtin_popcount in c++ or in any other language.
代码:
class Solution { public: vector<int> countBits(int num) { vector<int> dp(num + 1, 0); dp[0] = 0; for(int i = 1; i <= num; i ++) { if(isPowerOfTwo(i)) dp[i] = 1; else if(i % 2) dp[i] = dp[i - 1] + 1; else dp[i] = dp[i / 2]; } return dp; } bool isPowerOfTwo(int n) { if(n <= 0) return false; if((n & (n - 1)) == 0) return true; return false; } };
一会粗去跑步!
FH
标签:vector,int,number,num,Input,Output,Counting,Bits,Leetcode 来源: https://www.cnblogs.com/zlrrrr/p/10821575.html
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