87 lines
1.9 KiB
C
87 lines
1.9 KiB
C
#include<stdio.h>
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#include<time.h>
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#include<stdlib.h>
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#include<string.h>
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#include<assert.h>
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static inline double tstamp(void)
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{
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struct timespec tv;
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clock_gettime(CLOCK_REALTIME, &tv);
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return tv.tv_sec + tv.tv_nsec * 1.0e-9;
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}
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void shuffle(int *array, size_t n)
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{
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if (n > 1)
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{
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size_t i;
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// for (i = 0; i < n - 1; i++)
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for (i = 0; i < n ; i++)
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{
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// size_t j = i + rand() / (RAND_MAX / (n - i) + 1);
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size_t j = rand()%n;
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int t = array[j];
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array[j] = array[i];
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array[i] = t;
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}
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}
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}
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void init_access_c(int access[],size_t size)
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{
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int i;
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for(i=0;i<size;i++) access[i] = i;
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}
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void init_access_d(int access[],size_t size)
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{
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int i;
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for(i=0;i<size;i++) access[i] = size-i-1;
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}
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void init_access_a(int access[],size_t size)
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{
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init_access_c(access,size);
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shuffle(access,size);
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}
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void init_array(int t[],int N)
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{
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int i;
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for(i=0;i<N;i++) t[i] = i ;
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}
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long int sum_array(int t[],int access[],size_t size)
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{
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long int S=0;
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int i;
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for(i=0;i<size;i++) S += t[access[i]];
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return S;
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}
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int main(int argc,char * argv[])
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{
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double t1,t2;
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int * array; // tableau à sommer (contient les tous les entiers [0,SIZE-1]
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int * access;
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int i,size;
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long int S=0;
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if (argc !=3) {
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printf("%s -c|-d|-a SIZE\n",argv[0]);
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return 1;
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}
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size=strtol(argv[2],NULL,0);
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array=(int *)malloc(sizeof(int)*size);
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assert(array != NULL);
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access=(int *)malloc(sizeof(int)*size);
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assert(access != NULL);
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init_array(array,size);
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if (strcmp(argv[1],"-c") == 0)
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init_access_c(access,size);
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if (strcmp(argv[1],"-d") == 0)
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init_access_d(access,size);
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if (strcmp(argv[1],"-a") == 0)
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init_access_a(access,size);
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/* On somme les elements en accedant au tableau
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* sequentiellement (croissant/décroissant), ou
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* de manière aléatoire
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* */
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t1=tstamp();
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S= sum_array(array,access,size);
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t2=tstamp();
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printf("S=%ld %lf\n",S,(t2-t1));
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}
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