From 912d30b13ac1169c2491bea6134b883d7619b127 Mon Sep 17 00:00:00 2001 From: Shifa Maqsood Date: Sat, 12 Oct 2024 16:50:36 +0530 Subject: [PATCH] Create A* Search-Algorithm.ts add hacktoberfest label --- graph/A* Search-Algorithm.ts | 96 ++++++++++++++++++++++++++++++++++++ 1 file changed, 96 insertions(+) create mode 100644 graph/A* Search-Algorithm.ts diff --git a/graph/A* Search-Algorithm.ts b/graph/A* Search-Algorithm.ts new file mode 100644 index 00000000..884c6a3a --- /dev/null +++ b/graph/A* Search-Algorithm.ts @@ -0,0 +1,96 @@ +interface Node { + id: number; + g: number; // Cost from start to this node + h: number; // Heuristic cost from this node to target + f: number; // Total cost + parent?: Node; // Parent node for path reconstruction +} + +class GraphAStar { + private adjList: Map; + + constructor() { + this.adjList = new Map(); + } + + addVertex(vertex: number) { + this.adjList.set(vertex, []); + } + + addEdge(v1: number, v2: number) { + this.adjList.get(v1)?.push(v2); + this.adjList.get(v2)?.push(v1); // for undirected graph + } + + heuristic(node: number, target: number): number { + // This is a placeholder heuristic; replace with an actual heuristic function + return Math.abs(target - node); + } + + astar(start: number, target: number): number[] | null { + const openSet: Node[] = []; + const closedSet: Set = new Set(); + + const startNode: Node = { id: start, g: 0, h: this.heuristic(start, target), f: 0 }; + openSet.push(startNode); + + while (openSet.length) { + // Get the node with the lowest f score + openSet.sort((a, b) => a.f - b.f); + const currentNode = openSet.shift()!; + + if (currentNode.id === target) { + const path: number[] = []; + let temp: Node | undefined = currentNode; + + while (temp) { + path.push(temp.id); + temp = temp.parent; + } + + return path.reverse(); // Return reversed path + } + + closedSet.add(currentNode.id); + + const neighbors = this.adjList.get(currentNode.id) || []; + for (const neighborId of neighbors) { + if (closedSet.has(neighborId)) continue; + + const gScore = currentNode.g + 1; // Assuming cost is 1 for each edge + const hScore = this.heuristic(neighborId, target); + const fScore = gScore + hScore; + + const existingNodeIndex = openSet.findIndex(node => node.id === neighborId); + if (existingNodeIndex === -1 || fScore < openSet[existingNodeIndex].f) { + const neighborNode: Node = { + id: neighborId, + g: gScore, + h: hScore, + f: fScore, + parent: currentNode + }; + + if (existingNodeIndex === -1) { + openSet.push(neighborNode); + } else { + openSet[existingNodeIndex] = neighborNode; + } + } + } + } + + return null; // No path found + } +} + +// Example usage +const graphAStar = new GraphAStar(); +graphAStar.addVertex(1); +graphAStar.addVertex(2); +graphAStar.addVertex(3); +graphAStar.addVertex(4); +graphAStar.addEdge(1, 2); +graphAStar.addEdge(2, 3); +graphAStar.addEdge(3, 4); +console.log(graphAStar.astar(1, 4)); // Output: [1, 2, 3, 4] pFad - Phonifier reborn

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