FenwickTree class

A Binary Indexed Tree over num supporting point updates and range sums.

Constructors

FenwickTree(int size)

Creates a tree of size elements, all initialized to zero. Requires size >= 0. Audited: 2026-06-12 11:26 EDT

FenwickTree.fromList(List<num> values)

Creates a tree seeded with values, in O(n). Audited: 2026-06-12 11:26 EDT

Properties

hashCode → int

The hash code for this object.

no setter, inherited

length → int

Number of elements in the tree. Audited: 2026-06-12 11:26 EDT

no setter

runtimeType → Type

A representation of the runtime type of the object.

no setter, inherited

Methods

noSuchMethod(Invocation invocation) → dynamic

Invoked when a nonexistent method or property is accessed.

inherited

prefixSum(int index) → num

Sum of elements [0..index] inclusive (0-based), in O(log n). Requires 0 <= index < length. Audited: 2026-06-12 11:26 EDT

rangeSum(int low, int high) → num

Sum of elements [low..high] inclusive (0-based), in O(log n). Requires 0 <= low <= high < length.

toString() → String

A string representation of this object.

override

update(int index, num delta) → void

Adds delta to the element at index (0-based), in O(log n). Requires 0 <= index < length.

valueAt(int index) → num

The current value at index (0-based), in O(log n). Requires 0 <= index < length. Audited: 2026-06-12 11:26 EDT

Operators

operator ==(Object other) → bool

The equality operator.

inherited