Add solution #1353

Author: JoshCrozier

README.md

@@ -1,4 +1,4 @@
-# 1,249 LeetCode solutions in JavaScript
+# 1,250 LeetCode solutions in JavaScript
 
 [https://leetcodejavascript.com](https://leetcodejavascript.com)
 
@@ -1028,6 +1028,7 @@
 1349|[Maximum Students Taking Exam](./solutions/1349-maximum-students-taking-exam.js)|Hard|
 1351|[Count Negative Numbers in a Sorted Matrix](./solutions/1351-count-negative-numbers-in-a-sorted-matrix.js)|Easy|
 1352|[Product of the Last K Numbers](./solutions/1352-product-of-the-last-k-numbers.js)|Medium|
+1353|[Maximum Number of Events That Can Be Attended](./solutions/1353-maximum-number-of-events-that-can-be-attended.js)|Medium|
 1356|[Sort Integers by The Number of 1 Bits](./solutions/1356-sort-integers-by-the-number-of-1-bits.js)|Easy|
 1358|[Number of Substrings Containing All Three Characters](./solutions/1358-number-of-substrings-containing-all-three-characters.js)|Medium|
 1360|[Number of Days Between Two Dates](./solutions/1360-number-of-days-between-two-dates.js)|Easy|

solutions/1353-maximum-number-of-events-that-can-be-attended.js

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+/**
+ * 1353. Maximum Number of Events That Can Be Attended
+ * https://leetcode.com/problems/maximum-number-of-events-that-can-be-attended/
+ * Difficulty: Medium
+ *
+ * You are given an array of events where events[i] = [startDayi, endDayi]. Every event i starts
+ * at startDayi and ends at endDayi.
+ *
+ * You can attend an event i at any day d where startTimei <= d <= endTimei. You can only attend
+ * one event at any time d.
+ *
+ * Return the maximum number of events you can attend.
+ */
+
+/**
+ * @param {number[][]} events
+ * @return {number}
+ */
+var maxEvents = function(events) {
+  events.sort((a, b) => a[0] - b[0]);
+  const heap = [];
+  let result = 0;
+  let eventIndex = 0;
+  let currentDay = 1;
+
+  while (eventIndex < events.length || heap.length) {
+    while (eventIndex < events.length && events[eventIndex][0] <= currentDay) {
+      heapPush(heap, events[eventIndex][1]);
+      eventIndex++;
+    }
+
+    while (heap.length && heap[0] < currentDay) {
+      heapPop(heap);
+    }
+
+    if (heap.length) {
+      heapPop(heap);
+      result++;
+    }
+
+    currentDay++;
+  }
+
+  function heapPush(arr, val) {
+    arr.push(val);
+    let i = arr.length - 1;
+    while (i > 0) {
+      const parent = Math.floor((i - 1) / 2);
+      if (arr[parent] <= arr[i]) break;
+      [arr[parent], arr[i]] = [arr[i], arr[parent]];
+      i = parent;
+    }
+  }
+
+  function heapPop(arr) {
+    const result = arr[0];
+    arr[0] = arr[arr.length - 1];
+    arr.pop();
+    let i = 0;
+    while (true) {
+      const left = 2 * i + 1;
+      const right = 2 * i + 2;
+      let smallest = i;
+      if (left < arr.length && arr[left] < arr[smallest]) smallest = left;
+      if (right < arr.length && arr[right] < arr[smallest]) smallest = right;
+      if (smallest === i) break;
+      [arr[i], arr[smallest]] = [arr[smallest], arr[i]];
+      i = smallest;
+    }
+    return result;
+  }
+
+  return result;
+};