Create 1118-number-of-days-in-a-month.js

Author: everthis

1118-number-of-days-in-a-month.js

@@ -0,0 +1,60 @@
+/**
+
+Given a year Y and a month M, return how many days there are in that month.
+
+Example 1:
+
+Input: Y = 1992, M = 7
+Output: 31
+Example 2:
+
+Input: Y = 2000, M = 2
+Output: 29
+Example 3:
+
+Input: Y = 1900, M = 2
+Output: 28
+
+Note:
+
+1583 <= Y <= 2100
+1 <= M <= 12
+
+*/
+
+/**
+ * @param {number} Y
+ * @param {number} M
+ * @return {number}
+ */
+function numberOfDays(Y, M) {
+  switch (M) {
+    case 2:
+      return Y % 400 === 0 || (Y % 4 === 0 && Y % 100 !== 0) ? 29 : 28;
+    case 4:
+    case 6:
+    case 9:
+    case 11:
+      return 30;
+    default:
+      return 31;
+  }
+}
+
+// another
+
+/**
+ * @param {number} Y
+ * @param {number} M
+ * @return {number}
+ */
+const numberOfDays = function(Y, M) {
+  const d = new Date(Y, M - 1)
+  let num = 0
+  while(d.getMonth() === M - 1) {
+    num++
+    const n = d.getDate()
+    d.setDate(n + 1)
+  }
+  return num
+};