LeetCode 分类刷题 —— Bit Manipulation

Bit Manipulation 的 Tips:

• 异或的特性。第 136 题，第 268 题，第 389 题，第 421 题，

x ^ 0 = x
x ^ 11111……1111 = ~x
x ^ (~x) = 11111……1111
x ^ x = 0
a ^ b = c  => a ^ c = b  => b ^ c = a (交换律)
a ^ b ^ c = a ^ (b ^ c) = (a ^ b）^ c (结合律)

• 构造特殊 Mask，将特殊位置放 0 或 1。

1. 将 x 最右边的 n 位清零， x & ( ~0 << n )
2. 获取 x 的第 n 位值(0 或者 1)，(x >> n) & 1
3. 获取 x 的第 n 位的幂值，x & (1 << (n - 1))
4. 仅将第 n 位置为 1，x | (1 << n)
5. 仅将第 n 位置为 0，x & (~(1 << n))
6. 将 x 最高位至第 n 位(含)清零，x & ((1 << n) - 1)
7. 将第 n 位至第 0 位(含)清零，x & (~((1 << (n + 1)) - 1)）

• 有特殊意义的 & 位操作运算。第 260 题，第 201 题，第 318 题，第 371 题，第 397 题，第 461 题，第 693 题，

X & 1 == 1 判断是否是奇数(偶数)
X & = (X - 1) 将最低位(LSB)的 1 清零
X & -X 得到最低位(LSB)的 1
X & ~X = 0

Title	Solution	Difficulty	Time	Space	收藏
78. Subsets	Go	Medium	O(n^2)	O(n)	❤️
136. Single Number	Go	Easy	O(n)	O(1)
137. Single Number II	Go	Medium	O(n)	O(1)
169. Majority Element	Go	Easy	O(n)	O(1)	❤️
187. Repeated DNA Sequences	Go	Medium	O(n)	O(1)
190. Reverse Bits	Go	Easy	O(n)	O(1)
191. Number of 1 Bits	Go	Easy	O(n)	O(1)
201. Bitwise AND of Numbers Range	Go	Medium	O(n)	O(1)	❤️
231. Power of Two	Go	Easy	O(1)	O(1)
260. Single Number III	Go	Medium	O(n)	O(1)
268. Missing Number	Go	Easy	O(n)	O(1)
318. Maximum Product of Word Lengths	Go	Medium	O(n)	O(1)
338. Counting Bits	Go	Medium	O(n)	O(n)
342. Power of Four	Go	Easy	O(n)	O(1)
371. Sum of Two Integers	Go	Easy	O(n)	O(1)
389. Find the Difference	Go	Easy	O(n)	O(1)
393. UTF-8 Validation	Go	Medium	O(n)	O(1)
397. Integer Replacement	Go	Medium	O(n)	O(1)
401. Binary Watch	Go	Easy	O(1)	O(1)
405. Convert a Number to Hexadecimal	Go	Easy	O(n)	O(1)
421. Maximum XOR of Two Numbers in an Array	Go	Medium	O(n)	O(1)	❤️
461. Hamming Distance	Go	Easy	O(n)	O(1)
476. Number Complement	Go	Easy	O(n)	O(1)
477. Total Hamming Distance	Go	Medium	O(n)	O(1)
693. Binary Number with Alternating Bits	Go	Easy	O(n)	O(1)	❤️
756. Pyramid Transition Matrix	Go	Medium	O(n log n)	O(n)
762. Prime Number of Set Bits in Binary Representation	Go	Easy	O(n)	O(1)
784. Letter Case Permutation	Go	Easy	O(n)	O(1)
898. Bitwise ORs of Subarrays	Go	Easy	O(n)	O(1)