49 lines
1.0 KiB
C
49 lines
1.0 KiB
C
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#include <stdio.h>
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#include <inttypes.h>
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//Hello.
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uint64_t getHash(char const *s) {
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const int p = 31;
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uint64_t hash = 0, p_pow = 1;
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while(*s) {
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/* отнимаем 'a' от кода буквы и единицу прибавляем, чтобы у строки вида 'aaaaa' хэш был ненулевой */
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hash += (*s++ - 'a' + 1) * p_pow;
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p_pow *= p;
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}
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return hash;
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}
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uint64_t getHash2(char const *str)
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{
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uint64_t hash = 5381;
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int32_t c;
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while ((c = *str++))
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hash = ((hash<<5) + hash) + c;
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return hash;
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}
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uint64_t rol(uint64_t n, size_t shift) {
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return (n<<shift) | (n>>(64 - shift));
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}
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uint64_t getHash3(char const *s) {
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uint64_t result = 0x55555555;
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while (*s) {
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result ^= *s++;
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result = rol(result, 5);
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}
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return result;
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}
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int main(void)
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{
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char s[100] = {0};
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scanf("%s",s);
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printf("hash = %llu\n", getHash(s));
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printf("hash = %llu\n", getHash2(s));
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printf("hash = %llu\n", getHash3(s));
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return 0;
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}
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