【leetcode】1680. Concatenation of Consecutive Binary Numbers
题目如下:
Given an integer
n
, return the decimal value of the binary string formed by concatenating the binary representations of1
ton
in order, modulo109 + 7
.Example 1:
Input: n = 1 Output: 1 Explanation: "1" in binary corresponds to the decimal value 1.Example 2:
Input: n = 3 Output: 27 Explanation: In binary, 1, 2, and 3 corresponds to "1", "10", and "11". After concatenating them, we have "11011", which corresponds to the decimal value 27.Example 3:
Input: n = 12 Output: 505379714 Explanation: The concatenation results in "1101110010111011110001001101010111100". The decimal value of that is 118505380540. After modulo 109 + 7, the result is 505379714.Constraints:
1 <= n <= 105
解题思路:直接计算吧,能AC。
代码如下:
class Solution(object): def concatenatedBinary(self, n): """ :type n: int :rtype: int """ binStr = '' for i in range(1,n+1): binStr += bin(i)[2:] return int(binStr,2) % (10**9 + 7)