Lift Default impl for Config to one for DDSketch.

src/ddsketch.rs

@@ -47,6 +47,12 @@ pub struct DDSketch {
     zero_count: u64,
 }
 
+impl Default for DDSketch {
+    fn default() -> Self {
+        Self::new(Default::default())
+    }
+}
+
 // XXX: functions should return Option<> in the case of empty
 impl DDSketch {
     /// Construct a `DDSketch`. Requires a `Config` specifying the parameters of the sketch

src/store.rs

@@ -174,7 +174,7 @@ impl Store {
     }
 
     pub fn count(&self) -> u64 {
-        self.count as u64
+        self.count
     }
 
     pub fn merge(&mut self, other: &Store) {
@@ -203,7 +203,7 @@ impl Store {
             collapse_end_index = collapse_start_index;
         }
 
-        for key in (collapse_end_index as i32 + other.offset)..(other.max_key + 1) {
+        for key in (collapse_end_index + other.offset)..(other.max_key + 1) {
             self.bins[(key - self.offset) as usize] += other.bins[(key - other.offset) as usize]
         }