Add solution #3067

Author: JoshCrozier

README.md

@@ -2152,6 +2152,7 @@
 3047|[Find the Largest Area of Square Inside Two Rectangles](./solutions/3047-find-the-largest-area-of-square-inside-two-rectangles.js)|Medium|
 3065|[Minimum Operations to Exceed Threshold Value I](./solutions/3065-minimum-operations-to-exceed-threshold-value-i.js)|Easy|
 3066|[Minimum Operations to Exceed Threshold Value II](./solutions/3066-minimum-operations-to-exceed-threshold-value-ii.js)|Medium|
+3067|[Count Pairs of Connectable Servers in a Weighted Tree Network](./solutions/3067-count-pairs-of-connectable-servers-in-a-weighted-tree-network.js)|Medium|
 3068|[Find the Maximum Sum of Node Values](./solutions/3068-find-the-maximum-sum-of-node-values.js)|Hard|
 3105|[Longest Strictly Increasing or Strictly Decreasing Subarray](./solutions/3105-longest-strictly-increasing-or-strictly-decreasing-subarray.js)|Easy|
 3108|[Minimum Cost Walk in Weighted Graph](./solutions/3108-minimum-cost-walk-in-weighted-graph.js)|Hard|

solutions/3067-count-pairs-of-connectable-servers-in-a-weighted-tree-network.js

@@ -0,0 +1,64 @@
+/**
+ * 3067. Count Pairs of Connectable Servers in a Weighted Tree Network
+ * https://leetcode.com/problems/count-pairs-of-connectable-servers-in-a-weighted-tree-network/
+ * Difficulty: Medium
+ *
+ * You are given an unrooted weighted tree with n vertices representing servers numbered from 0
+ * to n - 1, an array edges where edges[i] = [ai, bi, weighti] represents a bidirectional edge
+ * between vertices ai and bi of weight weighti. You are also given an integer signalSpeed.
+ *
+ * Two servers a and b are connectable through a server c if:
+ * - a < b, a != c and b != c.
+ * - The distance from c to a is divisible by signalSpeed.
+ * - The distance from c to b is divisible by signalSpeed.
+ * - The path from c to b and the path from c to a do not share any edges.
+ *
+ * Return an integer array count of length n where count[i] is the number of server pairs that are
+ * connectable through the server i.
+ */
+
+/**
+ * @param {number[][]} edges
+ * @param {number} signalSpeed
+ * @return {number[]}
+ */
+var countPairsOfConnectableServers = function(edges, signalSpeed) {
+  const n = edges.length + 1;
+  const graph = Array.from({ length: n }, () => []);
+  for (const [u, v, w] of edges) {
+    graph[u].push([v, w]);
+    graph[v].push([u, w]);
+  }
+
+  const result = new Array(n).fill(0);
+  for (let i = 0; i < n; i++) {
+    result[i] = countValidPairs(i);
+  }
+  return result;
+
+  function countValidPairs(root) {
+    function dfs(node, parent, distance) {
+      let count = distance % signalSpeed === 0 ? 1 : 0;
+      for (const [next, weight] of graph[node]) {
+        if (next !== parent) {
+          count += dfs(next, node, distance + weight);
+        }
+      }
+      return count;
+    }
+
+    let totalPairs = 0;
+    const counts = [];
+    for (const [child, weight] of graph[root]) {
+      const count = dfs(child, root, weight);
+      counts.push(count);
+    }
+
+    let sum = 0;
+    for (const count of counts) {
+      totalPairs += sum * count;
+      sum += count;
+    }
+    return totalPairs;
+  }
+};