Selection Sort 6 7 Selection Sort C void

Selection. Sort 6

7 Selection Sort )ภาษา C( void selection. Sort(int d[], int n) { int k, i; for (k = n - 1; k > 0; k--) { int max. I =1; for (i = 0; i <= k; i++) if (d[i]> d[max. I]) max. I = i; int t = d[k]; d[k] = d[max. I]; d[max. I] = t; } }

#include <stdio. h> 8 #include <stdlib. h> #include <windows. h> int main(int argc, char *argv[]) { int i, k, n, repeat = 10; for( n = 0; n<=20000; n+=2000) { int *d = malloc( n * sizeof(int) ); long sum = 0; for (k=0; k<repeat; k++) { for (i=0; i<n; i++) d[i] = i; long start = Get. Tick. Count(); selection. Sort(d, n); sum += Get. Tick. Count() - start; } printf("%d t %f n", n, (float)sum/repeat); } system("PAUSE"); return 0; }

9 Selection Sort (ภาษา Java)

public class Test. Selection. Sort { public static void main(String[] args) { 10 int repeat = 10; for (int n = 0; n <= 20000; n += 2000) { int[]d = new int[n]; long sum = 0; for (int k = 0; k < repeat; k++) { for (int i = 0; i <n; i++) d[i] = i; { long start = System. current. Time. Millis(); selection. Sort(d); sum += System current. Time. Millis() - start; } System. out. printf("%d t %f n", (double)sum/repeat); } }

public class Test. Selection. Sort { public static void main(String[] args) { 11 int repeat = 10; for (int n = 0; n <= 20000; n += 2000) { int[]d = new int[n]; long sum = 0; for (int k = 0; k < repeat; k++) { for (int i = 0; i <n; i++) d[i] = i; { long start = System. current. Time. Millis(); selection. Sort(d); sum += System current. Time. Millis() - start; } System. out. printf("%d t %f n", (double)sum/repeat); } } for (int i = 0; i < 10000; i++) selection. Sort(new int[1]);

12 สงทำงาน พรอมบนทกผล ภาษา C : ใช GNU-C Compiler (3. 4. 2) ภาษา Java : ใช Java 6 (build 1. 6. 0_14 -b 08) Interpreted-only mode (option –Xint ตอนทำงาน ) Compilation to native code (บงคบ compile ดวยการเรยกเมทอดวำ ๆ สก 10 000 ครง ) Intel Core 2 Duo P 8400 2. 26 Ghz Ram 3 GB Windows XP

ใชจำนวนการทำงานของคำสงแทนเวลา 14 static int counter= 0; static void selection. Sort(int[] d) { counter = 1+d. length-1; for (int k = d. length-1; k > 0; k--) { int max. I =1; counter += 2 + k+1; for (int i = 0; i <= k; i++) { counter += 1; if (d[i] > d[max. I]) { max. I=i; counter+=1; } } counter += 3; int t = d[k]; d[k] = d[max. I]; d[max. I] = t; } }

15 เขยนโปรแกรมทดลองนบคำสง public class Test. Selection. Sort { public static void main(String[] args) { int repeat = 10; for (int n = 0; n <= 20000; n += 2000) { int[]d = new int[n]; long sum = 0; for (int k = 0; k < repeat; k++) { for (int i = 0; i <n; i++) d[i] = i; ; counter = 0; selection. Sort(d); sum += counter; } System. out. printf("%d t %f n", n, (double)sum/repeat); } }

17 นบเฉพาะคำสงตวแทน static intcounter= 0; static voidselection. Sort(int[] d) { for (int k = d. length-1; k > 0; k--) { int max. I =1; for (int i = 0; i <= k; i++) { counter += 1; if (d[i] > d[max. I]) { max. I = i; } } int t d[k]; d[k] = d[max. I]; d[max. I]=t; } }

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41 f(n) vs. g(n)

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44 L'Hôpital's rule

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49 สญกรณเชงเสน กำกบ (Asymptotic Notations) • little-o • little – omega • Big – Omega • Big - Theta

50 little-o

51 little – omega

52 Big - Theta

53 Big – O

54 Big – Omega

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76 ตวอยาง Insertion Sort

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82 ตวอยาง : Tower of Hanoi

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