Algorithms: Searching Tutorials and Code Examples - Page 8

Upper Bound in PHP

A boundary search finds an insertion position in a sorted array, including arrays with repeated values.

php

function upper_bound(array $a, int $target): int {
    alg_require(array_is_list($a));
    $n = count($a);
    alg_require((($n >= 0) && ($n <= 1000000)));
    alg_require((count($a) == $n));
    $lo = 0;
    $hi = $n;
    $mid = 0;
    while (($lo < $hi)) {
        $mid = alg_add($lo, intdiv(alg_sub($hi, $lo), 2));
        if (($a[$mid] <= $target)) {
            $lo = alg_add($mid, 1);

Nov 15, 2026 PHP

Algorithms: Searching

Lower Bound in Java

A boundary search finds an insertion position in a sorted array, including arrays with repeated values.

java

    static int lower_bound(int[] a, int target) {
        java.util.Objects.requireNonNull(a, "a");
        int n = a.length;
        alg_require(((n >= 0) && (n <= 1000000)));
        alg_require((a.length == n));
        int lo = 0;
        int hi = n;
        int mid = 0;
        while ((lo < hi)) {
            mid = Math.addExact(lo, (Math.subtractExact(hi, lo) / 2));
            if ((a[mid] < target)) {
                lo = Math.addExact(mid, 1);

Nov 15, 2026 Java

Algorithms: Searching

Lower Bound in JavaScript

A boundary search finds an insertion position in a sorted array, including arrays with repeated values.

javascript

function lower_bound(a, target) {
    alg_require(a instanceof Int32Array);
    alg_require(Number.isInteger(target) && target >= -2147483648 && target <= 2147483647);
    let n = a.length;
    alg_require(((n >= 0) && (n <= 1000000)));
    alg_require((a.length == n));
    let lo = 0;
    let hi = n;
    let mid = 0;
    while ((lo < hi)) {
        mid = alg_add(lo, Math.floor(alg_sub(hi, lo) / 2));
        if ((a[mid] < target)) {

Nov 15, 2026 javascript

Algorithms: Searching

Lower Bound in Python

A boundary search finds an insertion position in a sorted array, including arrays with repeated values.

python

def lower_bound(a: list[int], target: int) -> int:
    alg_require(isinstance(a, (list, tuple)) and len(a) <= 1000000)
    alg_require(type(target) is int and -2147483648 <= target <= 2147483647)
    n: int = len(a)
    alg_require(n >= 0 and n <= 1000000)
    alg_require(len(a) == n)
    lo: int = 0
    hi: int = n
    mid: int = 0
    while lo < hi:
        mid = lo + (hi - lo) // 2
        if a[mid] < target:

Nov 15, 2026 python

Algorithms: Searching

Lower Bound in C

A boundary search finds an insertion position in a sorted array, including arrays with repeated values.

c

int lower_bound(const int *a, size_t a_length, int target) {
    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; }
    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; }
    int lo = 0;

Nov 15, 2026 C