leetcode 231. Power of Two

leetcode
九章

题目描述

Given an integer, write a function to determine if it is a power of two.

Example 1:

Input: 1
Output: true 
Explanation: 20 = 1

Example 2:

Input: 16
Output: true
Explanation: 24 = 16

Example 3:

Input: 218
Output: false

Tags: Math, Bit Manipulation

Difficulty: Easy

答案



leetcode 762. Prime Number of Set Bits in Binary Representation

难度:Easy

leetcode
九章

题目描述

Given two integers L and R, find the count of numbers in the range [L, R] (inclusive) having a prime number of set bits in their binary
representation.

(Recall that the number of set bits an integer has is the number of 1s
present when written in binary. For example, 21 written in binary is 10101
which has 3 set bits. Also, 1 is not a prime.)

Example 1:

Input: L = 6, R = 10
Output: 4
Explanation:
6 -> 110 (2 set bits, 2 is prime)
7 -> 111 (3 set bits, 3 is prime)
9 -> 1001 (2 set bits , 2 is prime)
10->1010 (2 set bits , 2 is prime)

Example 2:

Input: L = 10, R = 15
Output: 5
Explanation:
10 -> 1010 (2 set bits, 2 is prime)
11 -> 1011 (3 set bits, 3 is prime)
12 -> 1100 (2 set bits, 2 is prime)
13 -> 1101 (3 set bits, 3 is prime)
14 -> 1110 (3 set bits, 3 is prime)
15 -> 1111 (4 set bits, 4 is not prime)

Note:

  1. L, R will be integers L <= R in the range [1, 10^6].
  2. R - L will be at most 10000.

Tags: Bit Manipulation

Difficulty: Easy

答案

leetcode 461. Hamming Distance

难度:Easy

leetcode
九章

题目描述

The Hamming distance between
two integers is the number of positions at which the corresponding bits are
different.

Given two integers x and y, calculate the Hamming distance.

Note:
0 ≤ x, y < 231.

Example:

Input: x = 1, y = 4

Output: 2

Explanation:
1   (0 0 0 1)
4   (0 1 0 0)
       ↑   ↑

The above arrows point to positions where the corresponding bits are different.

Tags: Bit Manipulation

Difficulty: Easy

答案

leetcode 268. Missing Number

难度:Easy

leetcode
九章

题目描述

Given an array containing n distinct numbers taken from 0, 1, 2, ..., n,
find the one that is missing from the array.

Example 1:

Input: [3,0,1]
Output: 2

Example 2:

Input: [9,6,4,2,3,5,7,0,1]
Output: 8

Note :
Your algorithm should run in linear runtime complexity. Could you implement it
using only constant extra space complexity?

Tags: Array, Math, Bit Manipulation

Difficulty: Easy

答案

leetcode 78. Subsets

难度:Middle

leetcode
九章

题目描述

Given a set of distinct integers, nums , return all possible subsets
(the power set).

Note: The solution set must not contain duplicate subsets.

Example:

Input: nums = [1,2,3]
Output:
[
  [3],
  [1],
  [2],
  [1,2,3],
  [1,3],
  [2,3],
  [1,2],
  []
]

Tags: Array, Backtracking, Bit Manipulation

Difficulty: Medium

答案


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