62 lines
1.2 KiB
Go
62 lines
1.2 KiB
Go
// File: recursion.go
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// Created Time: 2023-08-28
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// Author: Reanon (793584285@qq.com)
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package chapter_computational_complexity
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import "container/list"
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/* Recursion */
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func recur(n int) int {
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// Termination condition
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if n == 1 {
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return 1
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}
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// Recursive: recursive call
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res := recur(n - 1)
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// Return: return result
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return n + res
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}
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/* Simulate recursion with iteration */
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func forLoopRecur(n int) int {
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// Use an explicit stack to simulate the system call stack
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stack := list.New()
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res := 0
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// Recursive: recursive call
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for i := n; i > 0; i-- {
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// Simulate "recursive" by "pushing onto the stack"
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stack.PushBack(i)
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}
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// Return: return result
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for stack.Len() != 0 {
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// Simulate "return" by "popping from the stack"
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res += stack.Back().Value.(int)
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stack.Remove(stack.Back())
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}
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// res = 1+2+3+...+n
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return res
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}
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/* Tail recursion */
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func tailRecur(n int, res int) int {
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// Termination condition
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if n == 0 {
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return res
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}
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// Tail recursive call
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return tailRecur(n-1, res+n)
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}
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/* Fibonacci sequence: Recursion */
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func fib(n int) int {
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// Termination condition f(1) = 0, f(2) = 1
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if n == 1 || n == 2 {
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return n - 1
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}
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// Recursive call f(n) = f(n-1) + f(n-2)
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res := fib(n-1) + fib(n-2)
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// Return result f(n)
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return res
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}
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