51 lines
1.3 KiB
C
51 lines
1.3 KiB
C
#include <stdio.h>
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void *lsearch(const void *key, const void *base,
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size_t nmemb, size_t size,
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int (*compar)(const void *, const void *))
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{
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for (const char *p = base; nmemb--;)
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if (compar(key, p))
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p += size;
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else
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return (void *) p;
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return NULL;
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}
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void *binary_search(const void *key, const void *base,
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int lo, int hi, size_t size,
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int (*compar)(const void *, const void *))
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{
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if (lo > hi)
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return NULL;
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int mid = (lo + hi) >> 1;
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int c = compar(key, (char *) base + mid * size);
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if (c > 0)
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return binary_search(key, base, mid + 1, hi, size, compar);
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if (c < 0)
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return binary_search(key, base, lo, mid - 1, size, compar);
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return (char *) base + mid * size;
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}
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void *bsearch(const void *key, const void *base,
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size_t nmemb, size_t size,
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int (*compar)(const void *, const void *))
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{
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return binary_search(key, base, 0, nmemb, size, compar);
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}
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int cmp(const void *x, const void *y)
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{
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return *(int *) x - *(int *) y;
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}
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int main()
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{
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int a[] = {1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 88};
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int *l = lsearch(a + 7, a, sizeof(a) / sizeof(int), sizeof(int), cmp);
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int *b = bsearch(a + 7, a, sizeof(a) / sizeof(int), sizeof(int), cmp);
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printf("%zu %zu\n", l - a, b - a);
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return 0;
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}
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