From c40e2b263ea168c0eba745eb155f2807d0e425a7 Mon Sep 17 00:00:00 2001
From: TonalidadeHidrica <47710717+TonalidadeHidrica@users.noreply.github.com>
Date: Mon, 13 Jun 2022 11:02:49 +0900
Subject: [PATCH] Add len and is_empty to three containers

---
 src/fenwicktree.rs | 10 ++++++++++
 src/lazysegtree.rs | 12 ++++++++++++
 src/segtree.rs     | 12 ++++++++++++
 3 files changed, 34 insertions(+)

diff --git a/src/fenwicktree.rs b/src/fenwicktree.rs
index 9256ff0..a44b451 100644
--- a/src/fenwicktree.rs
+++ b/src/fenwicktree.rs
@@ -40,6 +40,14 @@ impl<T: Clone + std::ops::AddAssign<T>> FenwickTree<T> {
     {
         self.accum(r) - self.accum(l)
     }
+    /// Returns the number of elements.
+    pub fn len(&self) -> usize {
+        self.n
+    }
+    /// Returns if the container is empty.
+    pub fn is_empty(&self) -> bool {
+        self.len() == 0
+    }
 }
 
 #[cfg(test)]
@@ -53,6 +61,8 @@ mod tests {
         for i in 0..5 {
             bit.add(i, i as i64 + 1);
         }
+        assert_eq!(bit.len(), 5);
+        assert!(!bit.is_empty());
         assert_eq!(bit.sum(0, 5), 15);
         assert_eq!(bit.sum(0, 4), 10);
         assert_eq!(bit.sum(1, 3), 5);
diff --git a/src/lazysegtree.rs b/src/lazysegtree.rs
index 47020a8..dfe265c 100644
--- a/src/lazysegtree.rs
+++ b/src/lazysegtree.rs
@@ -254,6 +254,15 @@ impl<F: MapMonoid> LazySegtree<F> {
         } {}
         0
     }
+
+    /// Returns the number of elements.
+    pub fn len(&self) -> usize {
+        self.n
+    }
+    /// Returns if the container is empty.
+    pub fn is_empty(&self) -> bool {
+        self.len() == 0
+    }
 }
 
 pub struct LazySegtree<F>
@@ -341,6 +350,9 @@ mod tests {
         let mut segtree: LazySegtree<MaxAdd> = base.clone().into();
         check_segtree(&base, &mut segtree);
 
+        assert_eq!(segtree.len(), n);
+        assert!(!segtree.is_empty());
+
         let mut segtree = LazySegtree::<MaxAdd>::new(n);
         let mut internal = vec![i32::min_value(); n];
         for i in 0..n {
diff --git a/src/segtree.rs b/src/segtree.rs
index b543aa3..f50a81f 100644
--- a/src/segtree.rs
+++ b/src/segtree.rs
@@ -213,6 +213,15 @@ impl<M: Monoid> Segtree<M> {
     fn update(&mut self, k: usize) {
         self.d[k] = M::binary_operation(&self.d[2 * k], &self.d[2 * k + 1]);
     }
+
+    /// Returns the number of elements.
+    pub fn len(&self) -> usize {
+        self.n
+    }
+    /// Returns if the container is empty.
+    pub fn is_empty(&self) -> bool {
+        self.len() == 0
+    }
 }
 
 // Maybe we can use this someday
@@ -248,6 +257,9 @@ mod tests {
         let segtree: Segtree<Max<_>> = base.clone().into();
         check_segtree(&base, &segtree);
 
+        assert_eq!(segtree.len(), n);
+        assert!(!segtree.is_empty());
+
         let mut segtree = Segtree::<Max<_>>::new(n);
         let mut internal = vec![i32::min_value(); n];
         for i in 0..n {