moving min max

Keep track of the minimum or maximum value in a sliding window.

moving min max provides one data structure for keeping track of the minimum value and one for keeping track of the maximum value in a sliding window.

The algorithm is based on the description here.

The complexity of the operations are - O(1) for getting the minimum/maximum - O(1) for push - amortized O(1) for pop

```rust use movingminmax::MovingMin;

let mut movingmin = MovingMin::::new(); movingmin.push(2); movingmin.push(1); movingmin.push(3);

asserteq!(movingmin.min(), Some(&1)); asserteq!(movingmin.pop(), Some(2));

asserteq!(movingmin.min(), Some(&1)); asserteq!(movingmin.pop(), Some(1));

asserteq!(movingmin.min(), Some(&1)); asserteq!(movingmin.pop(), Some(3));

asserteq!(movingmin.min(), None); asserteq!(movingmin.pop(), None); ```

or

```rust use movingminmax::MovingMax;

let mut movingmax = MovingMax::::new(); movingmax.push(2); movingmax.push(3); movingmax.push(1);

asserteq!(movingmax.max(), Some(&3)); asserteq!(movingmax.pop(), Some(2));

asserteq!(movingmax.max(), Some(&3)); asserteq!(movingmax.pop(), Some(3));

asserteq!(movingmax.max(), Some(&3)); asserteq!(movingmax.pop(), Some(1));

asserteq!(movingmax.max(), None); asserteq!(movingmax.pop(), None); ```