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// Copyright 2015 The Bazel Authors. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
/// Returns the nth Fibonacci number.
///
/// # Examples
///
/// ```
/// fibonacci::fibonacci(5)
/// ```
pub fn fibonacci(n: u64) -> u64 {
if n < 2 {
return n;
}
let mut n1: u64 = 0;
let mut n2: u64 = 1;
for _ in 1..n {
let sum = n1 + n2;
n1 = n2;
n2 = sum;
}
n2
}
#[cfg(test)]
mod test {
use super::fibonacci;
#[test]
fn test_fibonacci() {
let numbers : Vec<u64> =
vec![0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144];
for (i, number) in numbers.iter().enumerate() {
assert_eq!(*number, fibonacci(i as u64));
}
}
}
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