Add solution #1154

Author: JoshCrozier

README.md

@@ -1,4 +1,4 @@
-# 1,154 LeetCode solutions in JavaScript
+# 1,155 LeetCode solutions in JavaScript
 
 [https://leetcodejavascript.com](https://leetcodejavascript.com)
 
@@ -902,6 +902,7 @@
 1145|[Binary Tree Coloring Game](./solutions/1145-binary-tree-coloring-game.js)|Medium|
 1146|[Snapshot Array](./solutions/1146-snapshot-array.js)|Medium|
 1147|[Longest Chunked Palindrome Decomposition](./solutions/1147-longest-chunked-palindrome-decomposition.js)|Hard|
+1154|[Day of the Year](./solutions/1154-day-of-the-year.js)|Easy|
 1161|[Maximum Level Sum of a Binary Tree](./solutions/1161-maximum-level-sum-of-a-binary-tree.js)|Medium|
 1189|[Maximum Number of Balloons](./solutions/1189-maximum-number-of-balloons.js)|Easy|
 1200|[Minimum Absolute Difference](./solutions/1200-minimum-absolute-difference.js)|Easy|

solutions/1154-day-of-the-year.js

@@ -0,0 +1,26 @@
+/**
+ * 1154. Day of the Year
+ * https://leetcode.com/problems/day-of-the-year/
+ * Difficulty: Easy
+ *
+ * Given a string date representing a Gregorian calendar date formatted as YYYY-MM-DD,
+ * return the day number of the year.
+ */
+
+/**
+ * @param {string} date
+ * @return {number}
+ */
+var dayOfYear = function(date) {
+  const daysInMonth = [31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31];
+  const [year, month, day] = date.split('-').map(Number);
+  const isLeapYear = year % 4 === 0 && (year % 100 !== 0 || year % 400 === 0);
+  if (isLeapYear) daysInMonth[1] = 29;
+
+  let result = day;
+  for (let i = 0; i < month - 1; i++) {
+    result += daysInMonth[i];
+  }
+
+  return result;
+};