Algorithms: Range Queries Tutorials and Code Examples - Page 8

Fenwick Tree Linear Build in Java

A Fenwick tree stores partial sums so point additions and prefix queries take logarithmic time..

java

    static int fenwick_build(int[] a, int[] tree) {
        java.util.Objects.requireNonNull(a, "a");
        java.util.Objects.requireNonNull(tree, "tree");
        int n = a.length;
        alg_require(((n >= 0) && (n <= 1000000)));
        alg_require((a.length == n));
        alg_require((tree.length == Math.addExact(n, 1)));
        int i = 0;
        int parent = 0;
        while ((i <= n)) {
            tree[i] = 0;
            i = Math.addExact(i, 1);

Nov 15, 2026 Java

Algorithms: Range Queries

Fenwick Tree Linear Build in JavaScript

A Fenwick tree stores partial sums so point additions and prefix queries take logarithmic time..

javascript

function fenwick_build(a, tree) {
    alg_require(a instanceof Int32Array);
    alg_require(tree instanceof Int32Array);
    let n = a.length;
    alg_require(((n >= 0) && (n <= 1000000)));
    alg_require((a.length == n));
    alg_require((tree.length == alg_add(n, 1)));
    let i = 0;
    let parent = 0;
    while ((i <= n)) {
        tree[i] = 0;
        i = alg_add(i, 1);

Nov 15, 2026 javascript

Algorithms: Range Queries

Fenwick Tree Linear Build in Python

A Fenwick tree stores partial sums so point additions and prefix queries take logarithmic time..

python

def fenwick_build(a: list[int], tree: list[int]) -> int:
    alg_require(isinstance(a, (list, tuple)) and len(a) <= 1000000)
    alg_require(isinstance(tree, list) and len(tree) <= 1000000)
    n: int = len(a)
    alg_require(n >= 0 and n <= 1000000)
    alg_require(len(a) == n)
    alg_require(len(tree) == n + 1)
    i: int = 0
    parent: int = 0
    while i <= n:
        tree[i] = 0
        i += 1

Nov 15, 2026 python

Algorithms: Range Queries

Fenwick Tree Linear Build in C

A Fenwick tree stores partial sums so point additions and prefix queries take logarithmic time..

c

int fenwick_build(const int *a, size_t a_length, int *tree, size_t tree_length) {
    int alg_error = 0;
    int alg_result = INT_MIN;
    errno = 0;
    if (a_length > 1000000 || (a_length && !a)) { errno = EINVAL; alg_result = INT_MIN; goto alg_cleanup; }
    if (tree_length > 1000000 || (tree_length && !tree)) { errno = EINVAL; alg_result = INT_MIN; goto alg_cleanup; }
    int n = (int)a_length;
    if (alg_error) { errno = ERANGE; alg_result = INT_MIN; goto alg_cleanup; }
    if (!(((n >= 0) && (n <= 1000000)))) { errno = EINVAL; alg_result = INT_MIN; goto alg_cleanup; }
    if (alg_error) { errno = ERANGE; alg_result = INT_MIN; goto alg_cleanup; }
    if (!(((int)a_length == n))) { errno = EINVAL; alg_result = INT_MIN; goto alg_cleanup; }
    if (alg_error) { errno = ERANGE; alg_result = INT_MIN; goto alg_cleanup; }

Nov 15, 2026 C

Algorithms: Range Queries

Fenwick Tree Linear Build in C++

A Fenwick tree stores partial sums so point additions and prefix queries take logarithmic time..

cpp

int fenwick_build(const std::vector<int>& a, std::vector<int>& tree) {
    alg_require(a.size() <= 1000000);
    alg_require(tree.size() <= 1000000);
    int n = (int)a.size();
    alg_require(((n >= 0) && (n <= 1000000)));
    alg_require(((int)a.size() == n));
    alg_require(((int)tree.size() == alg_add(n, 1)));
    int i = 0;
    int parent = 0;
    while ((i <= n)) {
        tree[i] = 0;
        i = alg_add(i, 1);

Nov 15, 2026 C++