Algorithms: Graph Algorithms Tutorials and Code Examples - Page 9

Depth First Search Reachability in Java

DFS follows a branch deeply before returning to pending branches.

java

    static int dfs_reachable(int[] graph, int n, int source) {
        java.util.Objects.requireNonNull(graph, "graph");
        alg_require(((n >= 0) && (n <= 1000000)));
        alg_require((graph.length == Math.multiplyExact(n, n)));
        alg_require(((n >= 1) && (source >= 0) && (source < n)));
        int[] seen = new int[alg_size(n)];
        int[] stack = new int[alg_size(n)];
        int top = 1;
        int count = 0;
        int u = 0;
        int v = 0;
        stack[0] = source;

Nov 15, 2026 Java

Algorithms: Graph Algorithms

Breadth First Search Shortest Path in Java

BFS explores an unweighted graph one distance layer at a time.

java

    static int bfs_distance(int[] graph, int n, int source, int target) {
        java.util.Objects.requireNonNull(graph, "graph");
        alg_require(((n >= 0) && (n <= 1000000)));
        alg_require((graph.length == Math.multiplyExact(n, n)));
        alg_require(((n >= 1) && (source >= 0) && (source < n)));
        alg_require(((target >= 0) && (target < n)));
        int[] distance = new int[alg_size(n)];
        int[] queue = new int[alg_size(n)];
        int v = 0;
        int u = 0;
        int head = 0;
        int tail = 1;

Nov 15, 2026 Java

Algorithms: Graph Algorithms

Floyd Warshall All Pairs Shortest Paths in JavaScript

Floyd-Warshall computes distances between every pair by gradually allowing more intermediate vertices.

javascript

function floyd_warshall(distance, n) {
    alg_require(distance instanceof Int32Array);
    alg_require(Number.isInteger(n) && n >= -2147483648 && n <= 2147483647);
    alg_require(((n >= 0) && (n <= 1000000)));
    alg_require((distance.length == alg_mul(n, n)));
    let k = 0;
    let i = 0;
    let j = 0;
    while ((k < n)) {
        i = 0;
        while ((i < n)) {
            j = 0;

Nov 15, 2026 javascript

Algorithms: Graph Algorithms

Floyd Warshall All Pairs Shortest Paths in Python

Floyd-Warshall computes distances between every pair by gradually allowing more intermediate vertices.

python

def floyd_warshall(distance: list[int], n: int) -> int:
    alg_require(isinstance(distance, list) and len(distance) <= 1000000)
    alg_require(type(n) is int and -2147483648 <= n <= 2147483647)
    alg_require(n >= 0 and n <= 1000000)
    alg_require(len(distance) == n * n)
    k: int = 0
    i: int = 0
    j: int = 0
    while k < n:
        i = 0
        while i < n:
            j = 0

Nov 15, 2026 python

Algorithms: Graph Algorithms

Depth First Search Reachability in JavaScript

DFS follows a branch deeply before returning to pending branches.

javascript

function dfs_reachable(graph, n, source) {
    alg_require(graph instanceof Int32Array);
    alg_require(Number.isInteger(n) && n >= -2147483648 && n <= 2147483647);
    alg_require(Number.isInteger(source) && source >= -2147483648 && source <= 2147483647);
    alg_require(((n >= 0) && (n <= 1000000)));
    alg_require((graph.length == alg_mul(n, n)));
    alg_require(((n >= 1) && (source >= 0) && (source < n)));
    let seen = new Int32Array(alg_size(n));
    let stack = new Int32Array(alg_size(n));
    let top = 1;
    let count = 0;
    let u = 0;

Nov 15, 2026 javascript