Create 233-number-of-digit-one.js

Author: everthis

233-number-of-digit-one.js

@@ -0,0 +1,19 @@
+/**
+ * @param {number} n
+ * @return {number}
+ */
+const countDigitOne = function(n) {
+  let count = 0
+  for (let m = 1; m <= n; m *= 10) {
+    const a = Math.floor(n / m)
+    const b = n % m
+    if (a % 10 > 1) {
+      count += (Math.floor(a / 10) + 1) * m
+    } else if (a % 10 === 1) {
+      count += Math.floor(a / 10) * m + b + 1
+    } else {
+      count += Math.floor(a / 10) * m
+    }
+  }
+  return count
+}