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An efficient Fibonacci function
static FIBONACCI_NUMBERS: [u64, ..93] = [0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55,
89, 144, 233, 377, 610, 987, 1597, 2584, 4181, 6765, 10946, 17711, 28657,
46368, 75025, 121393, 196418, 317811, 514229, 832040, 1346269, 2178309,
3524578, 5702887, 9227465, 14930352, 24157817, 39088169, 63245986,
102334155, 165580141, 267914296, 433494437, 701408733, 1134903170,
1836311903, 2971215073, 4807526976, 7778742049, 12586269025, 20365011074,
32951280099, 53316291173, 86267571272, 139583862445, 225851433717,
365435296162, 591286729879, 956722026041, 1548008755920, 2504730781961,
4052739537881, 6557470319842, 10610209857723, 17167680177565,
27777890035288, 44945570212853, 72723460248141, 117669030460994,
190392490709135, 308061521170129, 498454011879264, 806515533049393,
1304969544928657, 2111485077978050, 3416454622906707, 5527939700884757,
8944394323791464, 14472334024676221, 23416728348467685, 37889062373143906,
61305790721611591, 99194853094755497, 160500643816367088,
259695496911122585, 420196140727489673, 679891637638612258,
1100087778366101931, 1779979416004714189, 2880067194370816120,
4660046610375530309, 7540113804746346429];
pub fn fib(n: uint) -> Option<u64> {
if n < 93 {
Some(FIBONACCI_NUMBERS[n])
} else {
None
}
}
fn main() {
for n in range(0u, 94u) {
println!("fib({}) = {}", n, fib(n));
}
}
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