Rust、D、Go三者的Pk1

比较Rust、D、Go的单线程的运算、内存占用，Rust 1.0 alpha2(64位) ，D 2.066.1(ldc2编译器0.15.1(基于llvm3.6 msvc64))、Go 1.4.2(64位)，基于win7 64位平台. 为让内存有变化，特意加入字典或关联数组.

比较2点：1、使用内存，2、运行时长。

（注：虽然此题已在 以下两篇文章中以“数学公式”法做过比较，但对运行效率的比较意义不大。

  http://blog.csdn.net/iilovetopview/article/details/43745059

http://blog.csdn.net/iilovetopview/article/details/43913027

http://blog.csdn.net/iilovetopview/article/details/43960963

）

/*题目：

 有一个整数n,写一个函数f(n),返回0到n之间出现的"1"的个数。
  比如f(13)=6,现在f(1)=1,问下一个最大的f(n)=n的n是什么？

*/

 一、用穷举法查5万以内的数，并显示出函数结果。

1、Rust:

use std::time::duration::Duration;use std::collections::HashMap;fn main() { println!("(Rust Language) Please wait for some minutes,will found Next Fn(n) = n ,the n is:");  let r = Duration::span(fnx);  println!(" time :{} seconds",r.num_seconds());} fn fnx(){let ( mut pos,mut n ,mut count,mut y)=(0,1,0,0);  let  mut  aa: HashMap<usize, usize> =  HashMap::new();while(n <= 50000){ y+=1;   pos = Fx(n);aa.insert(n,pos); print!("{},",pos);if(n == pos) {count +=1;println!("n is: {0},  Fn(n) is:{1} ",n,pos);if(count >1) {break;}}if(y ==10){print!("\r\n");y =0;}n+=1;}println!("{} stop",n);}fn Fx (n: usize) -> usize {let mut total =0;  for i in 0..n+1{ total += Count(i); } return total;}  fn Count(n: usize) ->usize{  let (mut num,mut t) = (0,n);  while(t >= 1)  {  if(t%10 ==1){num +=1;}  t /= 10;  }    return num;}  

编译命令：rustc -O fnall5.rs
内存占用：

占用时长：

2、D：

module Fnall5;import std.stdio;import std.array;import std.conv;import std.datetime;void main(){ writeln("(D language) Please wait for some minutes,will found Next Fn(n) = n ,the n is:");int n =1;int count,pos,y;int[int] aa;StopWatch sw;sw.start();while(n <= 50000){y++;pos = Fn(n);aa[n] = pos;write(pos,",");if(n == pos) {count++;writeln("n is: ",n, " Fn(n) is: ",pos);if(count >1) break;}if(y == 10){y = 0;writeln();}n++;}sw.stop();writeln(" time :" , sw.peek().seconds," seconds");// msecs/1000.0writeln(n," stop");}int Fn(int n){int total;for(int i=0;i<=n;i++){total += Count(i);}return total;}int Count(int n){int num;for(int t = n;t >=1;t=t/10){if(t%10 == 1) num++;}return num;}

编译命令：ldc2 -m64  -O -release fnall5.d

内存占用：
占用时长：

3.Go:

package mainimport ("fmt""time")func main() {fmt.Println("(go Language)  Please wait for some minutes,will found Next Fn(n) = n ,the n is:")n := 1count :=0pos := 0 aa := make(map[int]int) y:=0t :=time.Now()for n =1;n<=50000;n++ {pos = Fn(n)aa[n] = posy++fmt.Print(pos,",")if n == pos {count++fmt.Println("n is :",n," Fn(n) is :",pos)if(count >1) {break}}if(y == 10){y =0fmt.Println()}}fmt.Println("time is :",time.Now().Sub(t).String())fmt.Println(n," stop")}func Fn(n int) int {var total intfor i:=0;i<=n;i++ {total += Count(i)}return total}func Count(n int) int{var num intfor t := n;t >=1;t=t/10 {if(t%10 == 1) {num++}}return num}

编译命令：go build -ldflags "-s -w" fnall5.go

内存占用：

占用时长：

----------------------------------------------------------------------------------------------

二、穷举法查10万以内的数。

1、Rust:（此处只列出与“5万”不同的代码）

 

fn fnx(){let ( mut pos,mut n ,mut count)=(0,1,0);  let  mut  aa: HashMap<usize, usize> =  HashMap::new();  while(n <=100000){   pos = Fx(n);aa.insert(n,pos);  if(n == pos) {count +=1;println!("n is: {0},  Fn(n) is:{1} ",n,pos);if(count >1) {break;}} n+=1;}println!("{} stop",n);}

内存占用：

运行时长：

2、D：

void main(){ writeln("(D language) Please wait for some minutes,will found Next Fn(n) = n ,the n is:");int n =1;int count,pos;int[int] aa;StopWatch sw;sw.start();while(n <= 100000){pos = Fn(n);aa[n] = pos;if(n == pos) {count++;writeln("n is: ",n, " Fn(n) is: ",pos);if(count >1) break;}n++;}sw.stop();writeln(" time :" , sw.peek().seconds," seconds");//1000.0writeln(n," stop");}

内存占用：

运行时长：

3、go:

func main() {fmt.Println("(go Language)  Please wait for some minutes,will found Next Fn(n) = n ,the n is:")n := 1count :=0pos := 0 aa := make(map[int]int) t :=time.Now()for n =1;n<=100000;n++ {pos = Fn(n)aa[n] = posif n == pos {count++fmt.Println("n is :",n," Fn(n) is :",pos)if(count >1) {break}}}fmt.Println("time is :",time.Now().Sub(t).String())fmt.Println(n," stop")}

内存占用：

运行时长：

三、继续求20万以内的结果(代码与10万的基本相同，只是数值修改为200000)

1、Rust:

内存占用：

运行时长：

2、D：

内存占用：

运行时长：

3、Go:

内存占用：

运行时长：