56 lines
689 B
C
56 lines
689 B
C
#include <stdio.h>
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/* Computes the length of Collatz sequences */
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unsigned int
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step (unsigned int x)
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{
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if (x % 2 == 0)
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{
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return (x / 2);
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}
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else
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{
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return (3 * x + 1);
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}
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}
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unsigned int
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nseq (unsigned int x0)
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{
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unsigned int i = 1, x;
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if (x0 == 1 || x0 == 0)
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return i;
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x = step (x0);
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while (x != 1 && x != 0)
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{
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x = step (x);
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i++;
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}
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return i;
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}
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int
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main (void)
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{
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unsigned int i, m = 0, im = 0;
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for (i = 1; i < 500000; i++)
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{
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unsigned int k = nseq (i);
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if (k > m)
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{
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m = k;
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im = i;
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printf ("sequence length = %u for %u\n", m, im);
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}
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}
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return 0;
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}
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