forked from github/server
88 lines
1.8 KiB
C
88 lines
1.8 KiB
C
#ifdef _MSC_VER
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#include <platform.h>
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#endif
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#include "variant.h"
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#include <stdlib.h>
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#include <limits.h>
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const variant frac_zero = { .sa = { 0, 1 } };
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const variant frac_one = { .sa = { 1, 1 } };
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static int gcd(int a, int b) {
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const int primes[] = { 3, 5, 7, 11, 13, 17, 19, 23, 0 };
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int i = 0, g = 1, p = 2;
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while (p && p <= a && p <= b) {
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if (a % p == 0 && b % p == 0) {
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a /= p;
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b /= p;
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g *= p;
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}
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else {
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p = primes[i++];
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}
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}
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return g;
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}
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static int lcm(int a, int b) {
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int x;
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if (a == b) return a;
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x = (a * b);
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x = (x > 0 ? x : -x) / gcd(a, b);
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return x;
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}
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bool frac_equal(variant a, variant b) {
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return frac_sign(frac_sub(a, b)) == 0;
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}
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variant frac_make(int num, int den)
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{
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variant v;
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int g = gcd(num, den);
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num /= g;
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den /= g;
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if (num < SHRT_MIN || num > SHRT_MAX || den < SHRT_MIN || den > SHRT_MAX) {
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int a = abs(num/SHRT_MIN) + 1;
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int b = abs(den/SHRT_MIN) + 1;
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if (b>a) a = b;
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num /= a;
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den /= a;
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}
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v.sa[0] = (short)num;
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v.sa[1] = (short)den;
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return v;
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}
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variant frac_add(variant a, variant b)
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{
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int num, den;
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den = lcm(a.sa[1], b.sa[1]);
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num = a.sa[0] * den / a.sa[1] + b.sa[0] * den / b.sa[1];
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return frac_make(num, den);
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}
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variant frac_sub(variant a, variant b)
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{
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b.sa[0] = -b.sa[0];
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return frac_add(a, b);
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}
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variant frac_mul(variant a, variant b)
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{
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return frac_make(a.sa[0] * b.sa[0], a.sa[1] * b.sa[1]);
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}
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variant frac_div(variant a, variant b)
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{
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return frac_make(a.sa[0] * b.sa[1], a.sa[1] * b.sa[0]);
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}
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int frac_sign(variant a) {
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if (a.sa[0] == 0) return 0;
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if (a.sa[0] > 0 && a.sa[1] > 0) return 1;
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if (a.sa[0] < 0 && a.sa[1] < 0) return 1;
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return -1;
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}
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