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Golang Program to round up the next previous power of 2.
Examples
For example, n = 12 => Previous number power of 2 is 8.
For example, n = 20 => Previous number power of 2 is 16.
Approach to solve this problem
Step 1 − Define a method that accepts a number n.
Step 2 − Perform n | (n >> k), where k is 1, 2, 4, 8, 16.
Step 3 − At the end, return n - (n >> 1).
Example
package main import "fmt" func PreviousPowOf2(n int) int{ n = n | (n >> 1) n = n | (n >> 2) n = n | (n >> 4) n = n | (n >> 8) n = n | (n >> 16) return n - (n >> 1) } func main(){ fmt.Printf("Previous round number, power of 2 for %d is %d\n", 20, PreviousPowOf2(20)) fmt.Printf("Previous round number, power of 2 for %d is %d\n", 12, PreviousPowOf2(12)) fmt.Printf("Previous round number, power of 2 for %d is %d\n", 131, PreviousPowOf2(131)) }
Output
Previous round number, power of 2 for 20 is 16 Previous round number, power of 2 for 12 is 8 Previous round number, power of 2 for 131 is 128
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