547. Friend Circles (axross#139)

Author: Kohei Asai

Diff for: solutions/friend_circles.ts

@@ -0,0 +1,29 @@
+// 547. Friend Circles
+// https://leetcode.com/problems/friend-circles/
+export default function findCircleNum(relationships: number[][]): number {
+  const friendCircles: Set<number>[] = [];
+  const visited = new Set<number>();
+
+  function traverse(person: number, friendCircle: Set<number>) {
+    if (visited.has(person)) return;
+
+    friendCircle.add(person);
+    visited.add(person);
+
+    for (const [other, isFriend] of relationships[person].entries()) {
+      if (isFriend !== 1) continue;
+
+      traverse(other, friendCircle);
+    }
+  }
+
+  for (const person of relationships.keys()) {
+    if (visited.has(person)) continue;
+
+    friendCircles.push(new Set());
+
+    traverse(person, friendCircles[friendCircles.length - 1]);
+  }
+
+  return friendCircles.length;
+}

Diff for: solutions/friend_circles_test.ts

@@ -0,0 +1,22 @@
+import { test } from "https://deno.land/std/testing/mod.ts";
+import { assertStrictEq } from "https://deno.land/std/testing/asserts.ts";
+import findCircleNum from "./friend_circles.ts";
+
+test("547. Friend Circles", () => {
+  assertStrictEq(findCircleNum([[1, 1, 0], [1, 1, 0], [0, 0, 1]]), 2);
+  assertStrictEq(findCircleNum([[1, 1, 0], [1, 1, 1], [0, 1, 1]]), 1);
+  assertStrictEq(
+    findCircleNum([
+      [1, 0, 1, 0, 0],
+      [0, 1, 0, 0, 1],
+      [1, 0, 1, 0, 0],
+      [0, 0, 0, 1, 1],
+      [0, 1, 0, 1, 1]
+    ]),
+    2
+  );
+  assertStrictEq(
+    findCircleNum([[1, 0, 0, 1], [0, 1, 1, 0], [0, 1, 1, 1], [1, 0, 1, 1]]),
+    1
+  );
+});