pub struct MovingAverage { len: usize, values: Vec::, current_index: usize, weights: Vec::, weights_total: u64, } impl MovingAverage { pub fn new() -> Self { let len = 19; let weights = vec![ 8, 16, 32, 64, 80, 85, 90, 95, 100, 100, 100, 95, 90, 85, 80, 64, 32, 16, 8 ]; let mut weight_total = 0; for v in &weights { weight_total += v; } Self { len: len, values: vec![0; len], current_index: 0, weights: weights, weights_total: weight_total } } pub fn insert(&mut self, value: u64) { self.values[self.current_index] = value; } pub fn average(&self) -> u64 { let mut sum: u64 = 0; for i in 0..self.len { let offset = (self.current_index + i) % self.len; let weight = self.weights[offset]; let value = self.values[offset]; sum += value * weight; } sum / self.weights_total } pub fn rotate(&mut self) { self.current_index = (self.current_index + 1) % self.len; } } #[cfg(test)] mod tests { use super::*; #[test] fn test_10000_all_zeroes() { let instance = MovingAverage::new(); assert_eq!(instance.average(), 0); } #[test] fn test_10001_all_some_value() { let mut instance = MovingAverage::new(); for _ in 0..20 { instance.insert(1000); instance.rotate(); } assert_eq!(instance.average(), 1000); } #[test] fn test_10002_half_some_value_half_zeroes() { let mut instance = MovingAverage::new(); for _ in 0..10 { instance.insert(1000); instance.rotate(); } assert_eq!(instance.average(), 540); } }