Given a range [m, n] where 0 <= m <= n <= 2147483647, return the bitwise AND of all numbers in this range, inclusive.
Example 1:
Input: [5,7] Output: 4
Example 2:
Input: [0,1] Output: 0
给定范围 [m, n],其中 0 <= m <= n <= 2147483647,返回此范围内所有数字的按位与(包含 m, n 两端点)。
示例 1:
输入: [5,7] 输出: 4
示例 2:
输入: [0,1] 输出: 0
44ms
1 class Solution { 2 func topDigit(_ n: Int) -> Int { 3 var n = n 4 while (n & (n-1)) != 0 { 5 n = (n & (n-1)) 6 } 7 return n 8 } 9 func rangeBitwiseAnd(_ m: Int, _ n: Int) -> Int { 10 guard m > 0 && n > 0 else { 11 return 0 12 } 13 var m2 = topDigit(m) 14 var n2 = topDigit(n) 15 16 if n2 != m2 { 17 return 0 18 } 19 20 return m2 | rangeBitwiseAnd(m-m2, n-m2) 21 } 22 }
48ms
1 class Solution { 2 func rangeBitwiseAnd(_ m: Int, _ n: Int) -> Int { 3 if m == 0 { 4 return 0 5 } 6 7 var m = m 8 var n = n 9 var factor = 1 10 11 while m != n { 12 m >>= 1 13 n >>= 1 14 factor <<= 1 15 } 16 17 return m * factor 18 } 19 }
52ms
1 class Solution { 2 func rangeBitwiseAnd(_ m: Int, _ n: Int) -> Int { 3 /* 4 0 - 0000 5 1 - 0001 6 2 - 0010 7 3 - 0011 8 4 - 0100 9 5 - 0101 10 6 - 0110 11 7 - 0111 12 8 - 1000 13 9 - 1001 14 10 - 1010 15 16 8..10 => 1000 17 */ 18 19 var m = m 20 var n = n 21 var i = 0 22 while m != n { 23 m >>= 1 24 n >>= 1 25 i += 1 26 } 27 return m << i 28 } 29 }
52ms
1 class Solution { 2 func rangeBitwiseAnd(_ m: Int, _ n: Int) -> Int { 3 return (n > m) ? (rangeBitwiseAnd(m / 2, n / 2) << 1) : m 4 5 } 6 }
56ms
1 class Solution { 2 func rangeBitwiseAnd(_ m: Int, _ n: Int) -> Int { 3 var plus = 1 4 var result = m & n 5 while m + plus < n { 6 result &= m + plus 7 plus += plus 8 } 9 return result 10 } 11 }
64ms
1 class Solution { 2 func rangeBitwiseAnd(_ m: Int, _ n: Int) -> Int { 3 // 101011101 4 // 101111001 5 6 var m = m 7 var n = n 8 var res = 0 9 var t = 1 10 for i in 0..<31 { 11 if m % 2 == 0 || n % 2 == 0 || m < n { 12 m = m >> 1 13 n = n >> 1 14 } else { 15 res += t 16 m = m >> 1 17 n = n >> 1 18 } 19 20 t *= 2 21 } 22 23 return res 24 } 25 }
原文地址:https://www.cnblogs.com/strengthen/p/10184197.html
时间: 2024-10-27 20:24:14