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#include "c23-fallback.h"
#include <stdio.h>
typedef struct fibonaccipair fibonaccipair;
struct fibonaccipair {
size_t prev;
size_t act;
};
fibonaccipair fiboNext(fibonaccipair ret) {
size_t res = ret.act + ret.prev;
ret.prev = ret.act;
ret.act = res;
return ret;
}
fibonaccipair fibonacci2(size_t n, fibonaccipair ret) {
if (n) {
return fibonacci2(n-1, fiboNext(ret));
} else
return ret;
}
fibonaccipair fibonacci3(size_t n, fibonaccipair ret) {
while (n --> 0) {
ret = fiboNext(ret);
}
return ret;
}
size_t fibonacci(size_t n) {
register fibonaccipair res = { 1, 1, };
if (n > 2) res = fibonacci2(n - 2, res);
return res.act;
}
int main(int argc, char* argv[argc+1]) {
for (int i = 1; i < argc; ++i) { // process args
size_t const n = strtoull(argv[i], nullptr, 0); // arg -> size_t
printf("fibonacci(%zu) is %zu\n",
n, fibonacci(n));
}
return EXIT_SUCCESS;
}
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