mirror of
https://github.com/golang/go
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130 lines
3.4 KiB
Go
130 lines
3.4 KiB
Go
/*
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions are met:
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* Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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* Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in the
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documentation and/or other materials provided with the distribution.
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* Neither the name of "The Computer Language Benchmarks Game" nor the
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name of "The Computer Language Shootout Benchmarks" nor the names of
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its contributors may be used to endorse or promote products derived
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from this software without specific prior written permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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POSSIBILITY OF SUCH DAMAGE.
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*/
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/* The Computer Language Benchmarks Game
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* http://shootout.alioth.debian.org/
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*
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* contributed by The Go Authors.
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* based on C program by Kevin Carson
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*/
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package main
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import (
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"flag"
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"fmt"
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)
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var n = flag.Int("n", 15, "depth")
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type Node struct {
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item int
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left, right *Node
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}
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type Arena struct {
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head *Node
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}
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var arena Arena
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func (n *Node) free() {
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if n.left != nil {
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n.left.free()
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}
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if n.right != nil {
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n.right.free()
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}
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n.left = arena.head
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arena.head = n
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}
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func (a *Arena) New(item int, left, right *Node) *Node {
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if a.head == nil {
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nodes := make([]Node, 3<<uint(*n))
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for i := 0; i < len(nodes)-1; i++ {
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nodes[i].left = &nodes[i+1]
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}
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a.head = &nodes[0]
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}
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n := a.head
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a.head = a.head.left
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n.item = item
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n.left = left
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n.right = right
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return n
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}
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func bottomUpTree(item, depth int) *Node {
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if depth <= 0 {
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return arena.New(item, nil, nil)
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}
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return arena.New(item, bottomUpTree(2*item-1, depth-1), bottomUpTree(2*item, depth-1))
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}
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func (n *Node) itemCheck() int {
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if n.left == nil {
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return n.item
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}
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return n.item + n.left.itemCheck() - n.right.itemCheck()
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}
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const minDepth = 4
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func main() {
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flag.Parse()
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maxDepth := *n
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if minDepth+2 > *n {
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maxDepth = minDepth + 2
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}
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stretchDepth := maxDepth + 1
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check := bottomUpTree(0, stretchDepth).itemCheck()
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fmt.Printf("stretch tree of depth %d\t check: %d\n", stretchDepth, check)
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longLivedTree := bottomUpTree(0, maxDepth)
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for depth := minDepth; depth <= maxDepth; depth += 2 {
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iterations := 1 << uint(maxDepth-depth+minDepth)
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check = 0
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for i := 1; i <= iterations; i++ {
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t := bottomUpTree(i, depth)
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check += t.itemCheck()
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t.free()
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t = bottomUpTree(-i, depth)
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check += t.itemCheck()
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t.free()
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}
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fmt.Printf("%d\t trees of depth %d\t check: %d\n", iterations*2, depth, check)
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}
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fmt.Printf("long lived tree of depth %d\t check: %d\n", maxDepth, longLivedTree.itemCheck())
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}
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