add UndirectedGraph

src/mol-math/graph/undirected-graph.ts

@@ -0,0 +1,51 @@
+/**
+ * Copyright (c) 2021 mol* contributors, licensed under MIT, See LICENSE file for more info.
+ *
+ * @author David Sehnal <david.sehnal@gmail.com>
+ */
+
+import { arraySetAdd } from '../../mol-util/array';
+
+export { UndirectedGraph };
+
+class UndirectedGraph<T extends string | number, S = T> {
+    vertices = new Map<T, S | undefined>();
+    edges = new Map<T, T[]>();
+
+    addVertex(a: T, s?: S) {
+        this.vertices.set(a, s);
+        if (!this.edges.has(a)) {
+            this.edges.set(a, []);
+        }
+    }
+
+    addEdge(a: T, b: T) {
+        arraySetAdd(this.edges.get(a)!, b);
+        arraySetAdd(this.edges.get(b)!, a);
+    }
+
+    /**
+     * Returns a connected component induced by a and
+     * its unique representative.
+     */
+    getComponent(a: T) {
+        let pivot = a;
+        const component: T[] = [];
+
+        const visited = new Set<T>();
+        const stack = [a];
+        while (stack.length > 0) {
+            const e = stack.pop()!;
+            component.push(e);
+            visited.add(e);
+            if (e < pivot) pivot = e;
+
+            for (const b of this.edges.get(e)!) {
+                if (visited.has(b)) continue;
+                stack.push(b);
+            }
+        }
+
+        return { pivot, component };
+    }
+}