From b4b228d17850ed76d10495ab6a55f9fd7c5a3195 Mon Sep 17 00:00:00 2001
From: NotLeonian <75620009+NotLeonian@users.noreply.github.com>
Date: Sun, 13 Apr 2025 22:07:09 +0900
Subject: [PATCH] Implement Debug for FenwickTree

---
 src/fenwicktree.rs | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/src/fenwicktree.rs b/src/fenwicktree.rs
index 4804fc4..5fedc13 100644
--- a/src/fenwicktree.rs
+++ b/src/fenwicktree.rs
@@ -1,3 +1,4 @@
+use std::fmt::{Debug, Error, Formatter};
 use std::ops::{Bound, RangeBounds};
 
 // Reference: https://en.wikipedia.org/wiki/Fenwick_tree
@@ -56,6 +57,20 @@ impl<T: Clone + std::ops::AddAssign<T>> FenwickTree<T> {
     }
 }
 
+impl<T: Clone + Debug + std::ops::AddAssign<T>> Debug for FenwickTree<T> {
+    fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error> {
+        f.debug_struct("FenwickTree")
+            .field("n", &self.n)
+            .field(
+                "accum",
+                &(1..=self.n).map(|i| self.accum(i)).collect::<Vec<_>>(),
+            )
+            .field("e", &self.e)
+            .finish()?;
+        Ok(())
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;