68 lines
2.0 KiB
C
68 lines
2.0 KiB
C
/*
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* This is an optimized version of the following C++ program:
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*
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* http://keithlea.com/javabench/src/cpp/hash.cpp
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*
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* Keith in his benchmark (http://keithlea.com/javabench/data) showed that the
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* Java implementation is twice as fast as the C++ version. In fact, this is
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* only because the C++ implementation is substandard. Most importantly, Keith
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* is using "sprintf()" to convert an integer to a string, which is known to be
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* extremely inefficient.
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*/
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#include <stdio.h>
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#include "khash.h"
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KHASH_MAP_INIT_STR(str, int)
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inline void int2str(int c, int base, char *ret)
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{
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const char *tab = "0123456789abcdef";
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if (c == 0) ret[0] = '0', ret[1] = 0;
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else {
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int l, x, y;
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char buf[16];
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for (l = 0, x = c < 0? -c : c; x > 0; x /= base) buf[l++] = tab[x%base];
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if (c < 0) buf[l++] = '-';
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for (x = l - 1, y = 0; x >= 0; --x) ret[y++] = buf[x];
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ret[y] = 0;
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}
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}
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int main(int argc, char *argv[])
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{
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int i, l, n = 1000, ret;
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khash_t(str) *h, *h2;
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khint_t k;
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h = kh_init(str);
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h2 = kh_init(str);
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if (argc > 1) n = atoi(argv[1]);
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for (i = 0; i < 10000; ++i) {
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char buf[32];
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strcpy(buf, "foo_");
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int2str(i, 10, buf+4);
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k = kh_put(str, h, strdup(buf), &ret);
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kh_val(h, k) = i;
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}
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for (i = 0; i < n; ++i) {
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for (k = kh_begin(h); k != kh_end(h); ++k) {
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if (kh_exist(h, k)) {
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khint_t k2 = kh_put(str, h2, kh_key(h, k), &ret);
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if (ret) { // absent
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kh_key(h2, k2) = strdup(kh_key(h, k));
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kh_val(h2, k2) = kh_val(h, k);
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} else kh_val(h2, k2) += kh_val(h, k);
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}
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}
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}
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k = kh_get(str, h, "foo_1"); printf("%d", kh_val(h, k));
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k = kh_get(str, h, "foo_9999"); printf(" %d", kh_val(h, k));
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k = kh_get(str, h2, "foo_1"); printf(" %d", kh_val(h2, k));
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k = kh_get(str, h2, "foo_9999"); printf(" %d\n", kh_val(h2, k));
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for (k = kh_begin(h); k != kh_end(h); ++k)
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if (kh_exist(h, k)) free((char*)kh_key(h, k));
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for (k = kh_begin(h2); k != kh_end(h2); ++k)
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if (kh_exist(h2, k)) free((char*)kh_key(h2, k));
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kh_destroy(str, h);
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kh_destroy(str, h2);
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return 0;
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}
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