Problem
Given an integer, write a function to determine if it is a power of two.
example 1
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Input: 1
Output: true
Explanation: 2^0 = 1
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example 2
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Input: 16
Output: true
Explanation: 2^4 = 16
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example 3
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Input: 218
Output: false
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Solution
Recursion
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func isPowerOfTwo(n int) bool {
if n<=0 {
return false
}
if n == 1 {
return true
}
if n%2 == 1{
return false
}
return isPowerOfTwo(n>>1)
}
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For
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func isPowerOfTwo(n int) bool {
if n<=0 {
return false
}
for ;n >1;n=n>>1 {
if n%2 == 1 {
return false
}
}
return true
}
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