Add solution #616

Author: JoshCrozier

README.md

@@ -576,6 +576,7 @@
 606|[Construct String from Binary Tree](./solutions/0606-construct-string-from-binary-tree.js)|Easy|
 609|[Find Duplicate File in System](./solutions/0609-find-duplicate-file-in-system.js)|Medium|
 611|[Valid Triangle Number](./solutions/0611-valid-triangle-number.js)|Medium|
+616|[Add Bold Tag in String](./solutions/0616-add-bold-tag-in-string.js)|Medium|
 617|[Merge Two Binary Trees](./solutions/0617-merge-two-binary-trees.js)|Easy|
 621|[Task Scheduler](./solutions/0621-task-scheduler.js)|Medium|
 622|[Design Circular Queue](./solutions/0622-design-circular-queue.js)|Medium|

solutions/0616-add-bold-tag-in-string.js

@@ -0,0 +1,61 @@
+/**
+ * 616. Add Bold Tag in String
+ * https://leetcode.com/problems/add-bold-tag-in-string/
+ * Difficulty: Medium
+ *
+ * You are given a string s and an array of strings words.
+ *
+ * You should add a closed pair of bold tag <b> and </b> to wrap the substrings in s that
+ * exist in words.
+ * - If two such substrings overlap, you should wrap them together with only one pair of
+ *   closed bold-tag.
+ * - If two substrings wrapped by bold tags are consecutive, you should combine them.
+ *
+ * Return s after adding the bold tags.
+ */
+
+/**
+ * @param {string} s
+ * @param {string[]} words
+ * @return {string}
+ */
+var addBoldTag = function(s, words) {
+  const boldIntervals = [];
+
+  for (const word of words) {
+    let start = s.indexOf(word);
+    while (start !== -1) {
+      boldIntervals.push([start, start + word.length]);
+      start = s.indexOf(word, start + 1);
+    }
+  }
+
+  if (!boldIntervals.length) return s;
+
+  boldIntervals.sort((a, b) => a[0] - b[0] || a[1] - b[1]);
+
+  const mergedIntervals = [];
+  let [currentStart, currentEnd] = boldIntervals[0];
+
+  for (let i = 1; i < boldIntervals.length; i++) {
+    const [nextStart, nextEnd] = boldIntervals[i];
+    if (nextStart <= currentEnd) {
+      currentEnd = Math.max(currentEnd, nextEnd);
+    } else {
+      mergedIntervals.push([currentStart, currentEnd]);
+      [currentStart, currentEnd] = [nextStart, nextEnd];
+    }
+  }
+  mergedIntervals.push([currentStart, currentEnd]);
+
+  let result = '';
+  let lastEnd = 0;
+  for (const [start, end] of mergedIntervals) {
+    result += s.slice(lastEnd, start) + '<b>' + s.slice(start, end) + '</b>';
+    lastEnd = end;
+  }
+
+  result += s.slice(lastEnd);
+
+  return result;
+};