Graphs.js

class Graph {
    constructor () {
        this.adjacencyList = {};
    }

    addVertex (vertex) {
        if (!this.adjacencyList[vertex]) this.adjacencyList[vertex] = [];
    }

    addEdge (vertex1, vertex2) {
        if (this.adjacencyList[vertex1] && this.adjacencyList[vertex2]) {
            this.adjacencyList[vertex1].push(vertex2);
            this.adjacencyList[vertex2].push(vertex1);
        }
    }

    removeEdge (vertex1, vertex2) {
        if (this.adjacencyList[vertex1] && this.adjacencyList[vertex2]) {
            this.adjacencyList[vertex1] = this.adjacencyList[vertex1].filter(v => v !== vertex2);
            this.adjacencyList[vertex2] = this.adjacencyList[vertex2].filter(v => v !== vertex1);
        }
    }

    removeVertex (vertex) {
        if (this.adjacencyList[vertex]) {
            while (this.adjacencyList[vertex].length) {
                const adjacentVertex = this.adjacencyList[vertex].pop();
                this.removeEdge(vertex, adjacentVertex);
            }
            delete this.adjacencyList[vertex];
        }
    }

    depthFirstSearchRecursive (vertex) {
        const result = [];
        const visited = {};
        const adjacencyList = this.adjacencyList;

        function helper (v) {
            if (!v) return null;
            result.push(v);
            visited[v] = true;

            adjacencyList[v].forEach(neighbor => {
                if (!visited[neighbor]) {
                    return helper(neighbor);
                }
            });
        }

        helper(vertex);

        return result;
    }

    depthFirstSearchIterative (vertex) {
        const result = [];
        const visited = {};
        const stack = [ vertex ];
        visited[vertex] = true;

        while (stack.length) {
            const vertex = stack.pop();
            result.push(vertex);
            this.adjacencyList[vertex].forEach(neighbor => {
                if (!visited[neighbor]) {
                    visited[neighbor] = true;
                    stack.push(neighbor);
                }
            });
        }

        return result;
    }

    breadthFirstSearch (vertex) {
        const result = [];
        const visited = {};
        const queue = [ vertex ];
        visited[vertex] = true;

        while (queue.length) {
            const vertex = queue.shift();
            result.push(vertex);
            this.adjacencyList[vertex].forEach(neighbor => {
                if (!visited[neighbor]) {
                    visited[neighbor] = true;
                    queue.push(neighbor);
                }
            });
        }

        return result;
    }
}