Add solution #2406

JoshCrozier · JoshCrozier · commit ed613746c7b3 · 2025-08-16T08:22:34.000-05:00
diff --git a/README.md b/README.md
@@ -2182,6 +2182,7 @@
 2403|[Minimum Time to Kill All Monsters](./solutions/2403-minimum-time-to-kill-all-monsters.js)|Hard|
 2404|[Most Frequent Even Element](./solutions/2404-most-frequent-even-element.js)|Easy|
 2405|[Optimal Partition of String](./solutions/2405-optimal-partition-of-string.js)|Medium|
+2406|[Divide Intervals Into Minimum Number of Groups](./solutions/2406-divide-intervals-into-minimum-number-of-groups.js)|Medium|
 2408|[Design SQL](./solutions/2408-design-sql.js)|Medium|
 2409|[Count Days Spent Together](./solutions/2409-count-days-spent-together.js)|Easy|
 2410|[Maximum Matching of Players With Trainers](./solutions/2410-maximum-matching-of-players-with-trainers.js)|Medium|
diff --git a/solutions/2406-divide-intervals-into-minimum-number-of-groups.js b/solutions/2406-divide-intervals-into-minimum-number-of-groups.js
@@ -0,0 +1,39 @@
+/**
+ * 2406. Divide Intervals Into Minimum Number of Groups
+ * https://leetcode.com/problems/divide-intervals-into-minimum-number-of-groups/
+ * Difficulty: Medium
+ *
+ * You are given a 2D integer array intervals where intervals[i] = [lefti, righti] represents
+ * the inclusive interval [lefti, righti].
+ *
+ * You have to divide the intervals into one or more groups such that each interval is in
+ * exactly one group, and no two intervals that are in the same group intersect each other.
+ *
+ * Return the minimum number of groups you need to make.
+ *
+ * Two intervals intersect if there is at least one common number between them. For example,
+ * the intervals [1, 5] and [5, 8] intersect.
+ */
+
+/**
+ * @param {number[][]} intervals
+ * @return {number}
+ */
+var minGroups = function(intervals) {
+  const events = [];
+  for (const [start, end] of intervals) {
+    events.push([start, 1]);
+    events.push([end + 1, -1]);
+  }
+
+  events.sort((a, b) => a[0] === b[0] ? a[1] - b[1] : a[0] - b[0]);
+
+  let activeIntervals = 0;
+  let result = 0;
+  for (const [time, change] of events) {
+    activeIntervals += change;
+    result = Math.max(result, activeIntervals);
+  }
+
+  return result;
+};
