Add solution #811

Author: JoshCrozier

README.md

@@ -619,6 +619,7 @@
 808|[Soup Servings](./0808-soup-servings.js)|Medium|
 809|[Expressive Words](./0809-expressive-words.js)|Medium|
 810|[Chalkboard XOR Game](./0810-chalkboard-xor-game.js)|Hard|
+811|[Subdomain Visit Count](./0811-subdomain-visit-count.js)|Medium|
 819|[Most Common Word](./0819-most-common-word.js)|Easy|
 821|[Shortest Distance to a Character](./0821-shortest-distance-to-a-character.js)|Easy|
 824|[Goat Latin](./0824-goat-latin.js)|Easy|

solutions/0811-subdomain-visit-count.js

@@ -0,0 +1,55 @@
+/**
+ * 811. Subdomain Visit Count
+ * https://leetcode.com/problems/subdomain-visit-count/
+ * Difficulty: Medium
+ *
+ * A website domain "discuss.leetcode.com" consists of various subdomains. At the top level, we have
+ * "com", at the next level, we have "leetcode.com" and at the lowest level, "discuss.leetcode.com".
+ * When we visit a domain like "discuss.leetcode.com", we will also visit the parent domains
+ * "leetcode.com" and "com" implicitly.
+ *
+ * A count-paired domain is a domain that has one of the two formats "rep d1.d2.d3" or "rep d1.d2"
+ * where rep is the number of visits to the domain and d1.d2.d3 is the domain itself.
+ *
+ * For example, "9001 discuss.leetcode.com" is a count-paired domain that indicates that
+ * discuss.leetcode.com was visited 9001 times.
+ *
+ * Given an array of count-paired domains cpdomains, return an array of the count-paired domains of
+ * each subdomain in the input. You may return the answer in any order.
+ */
+
+/**
+ * @param {string[]} cpdomains
+ * @return {string[]}
+ */
+var subdomainVisits = function(cpdomains) {
+  const domainCount = new Map();
+
+  for (const cpdomain of cpdomains) {
+    const [countStr, domain] = cpdomain.split(' ');
+    const count = parseInt(countStr);
+    const subdomains = getSubdomains(domain);
+
+    for (const subdomain of subdomains) {
+      domainCount.set(subdomain, (domainCount.get(subdomain) || 0) + count);
+    }
+  }
+
+  const result = [];
+  for (const [domain, count] of domainCount) {
+    result.push(`${count} ${domain}`);
+  }
+
+  return result;
+};
+
+function getSubdomains(domain) {
+  const parts = domain.split('.');
+  const subdomains = [];
+
+  for (let i = 0; i < parts.length; i++) {
+    subdomains.push(parts.slice(i).join('.'));
+  }
+
+  return subdomains;
+}