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LeetCode 190. Reverse Bits

2021/12/14に公開約1,200字

Question

Reverse bits of a given 32 bits unsigned integer.

Note:

- Note that in some languages, such as Java, there is no unsigned integer type. In this case, both input and output will be given as a signed integer type. They should not affect your implementation, as the integer's internal binary representation is the same, whether it is signed or unsigned.
- In Java, the compiler represents the signed integers using 2's complement notation. Therefore, in Example 2 above, the input represents the signed integer -3 and the output represents the signed integer -1073741825.

与えられた32ビット符号なし整数nを反転する問題

Code

class Solution {
    // you need treat n as an unsigned value
    fun reverseBits(n:Int):Int {
        var reversed = 0
        var cn = n
        repeat(32) {
            val bottomBit = cn and 1
            reversed = reversed shl 1
            reversed = reversed or bottomBit
            cn = cn shr 1
        }
        return reversed
    }
}

Profile

  • Runtime: 112 ms
  • Memory Usage: 32.2 MB

Submission

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Discussion

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