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fix: fibonacci_fast.cpp fixes

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Panquesito7
2020-06-23 18:22:21 -05:00
parent da18b90498
commit 01c5278911
1 changed files with 10 additions and 12 deletions
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22
math/fibonacci_fast.cpp
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@@ -28,22 +28,20 @@
/** Algorithm */
uint64_t fib(uint64_t n) {
// Array of computed fibonacci numbers */
static uint64_t numbers[MAX] = {0};
static uint64_t f1 = 1, f2 = 1; // using static keyword will retain the values of f1 and f2 for the next function call.
if (n == 0)
if (n <= 2)
return f2;
if (n >= 93) {
std::err << "Cannot compute for n>93 due to limit of 64-bit integers\n";
return 0;
if (n == 1 || n == 2)
return (numbers[n] = 1);
}
if (numbers[n])
return numbers[n];
uint64_t temp = f2; // we do not need temp to be static
f2 += f1;
f1 = temp;
uint64_t k = (n % 2 != 0) ? (n + 1) / 2 : n / 2;
numbers[n] = (n % 2 != 0) ? (fib(k) * fib(k) + fib(k - 1) * fib(k - 1))
: (2 * fib(k - 1) + fib(k)) * fib(k);
return numbers[n];
return f2;
}
/** Main function */