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57 lines
1.5 KiB
C
57 lines
1.5 KiB
C
#include "genlib.h"
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#include "log.h"
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/*determines the greatest prime factor of an integer*/
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int maxfactor(int n) {
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clock_t t = clock();
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log_info("RESULT = in progress, n = %d", n);
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int test_fact(int* pnum, int fact, int* pmaxfac);
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int lnum, fact;
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int maxfac;
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maxfac = 1;
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lnum = n;
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if (lnum != 0 && lnum != 1) {
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fact = 2;
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if (test_fact(&lnum, fact, &maxfac)) {
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fact = 3;
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if (test_fact(&lnum, fact, &maxfac)) {
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fact = 5;
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for (;;) {
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if (!test_fact(&lnum, fact, &maxfac))
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break;
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fact += 2;
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if (!test_fact(&lnum, fact, &maxfac))
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break;
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fact += 4;
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}
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}
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}
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if (lnum != 1) {
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if (lnum > maxfac)
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maxfac = lnum;
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}
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}
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t = clock() - t;
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double time_taken = ((double)t)/CLOCKS_PER_SEC; // calculate the elapsed time
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double* total_ram = malloc(sizeof(double));
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getTotalVirtualMem(total_ram);
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double* used_ram = malloc(sizeof(double));
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getVirtualMemUsed(used_ram);
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log_info("TOTAL VIRTUAL MEM = %5.1f MB, USED VIRTUAL MEM = %5.1f MB, USED VIRTUAL MEM BY CURRENT PROCESS = %d MB",
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*total_ram, *used_ram, getVirtualMemUsedByCurrentProcess());
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free(total_ram);
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free(used_ram);
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log_info("RESULT = success, maxfac = %d, ELAPSED = %f seconds", maxfac, time_taken);
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return maxfac;
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}
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