Add solution #1012

Author: JoshCrozier

Diff for: README.md

@@ -1,4 +1,4 @@
-# 1,086 LeetCode solutions in JavaScript
+# 1,087 LeetCode solutions in JavaScript
 
 [https://leetcode.com/](https://leetcode.com/)
 
@@ -820,6 +820,7 @@
 1009|[Complement of Base 10 Integer](./solutions/1009-complement-of-base-10-integer.js)|Easy|
 1010|[Pairs of Songs With Total Durations Divisible by 60](./solutions/1010-pairs-of-songs-with-total-durations-divisible-by-60.js)|Medium|
 1011|[Capacity To Ship Packages Within D Days](./solutions/1011-capacity-to-ship-packages-within-d-days.js)|Medium|
+1012|[Numbers With Repeated Digits](./solutions/1012-numbers-with-repeated-digits.js)|Hard|
 1022|[Sum of Root To Leaf Binary Numbers](./solutions/1022-sum-of-root-to-leaf-binary-numbers.js)|Easy|
 1023|[Camelcase Matching](./solutions/1023-camelcase-matching.js)|Medium|
 1028|[Recover a Tree From Preorder Traversal](./solutions/1028-recover-a-tree-from-preorder-traversal.js)|Hard|

Diff for: solutions/1012-numbers-with-repeated-digits.js

@@ -0,0 +1,48 @@
+/**
+ * 1012. Numbers With Repeated Digits
+ * https://leetcode.com/problems/numbers-with-repeated-digits/
+ * Difficulty: Hard
+ *
+ * Given an integer n, return the number of positive integers in the range [1, n] that have at
+ * least one repeated digit.
+ */
+
+/**
+ * @param {number} n
+ * @return {number}
+ */
+var numDupDigitsAtMostN = function(n) {
+  const digits = String(n).split('').map(Number);
+  const length = digits.length;
+  let result = 0;
+
+  function calculatePermutations(size, available) {
+    let total = 1;
+    for (let i = 0; i < size; i++) {
+      total *= available - i;
+    }
+    return total;
+  }
+
+  for (let i = 1; i < length; i++) {
+    result += 9 * calculatePermutations(i - 1, 9);
+  }
+
+  const used = new Set();
+  for (let i = 0; i < length; i++) {
+    const start = i === 0 ? 1 : 0;
+    const limit = digits[i];
+
+    for (let d = start; d < limit; d++) {
+      if (!used.has(d)) {
+        result += calculatePermutations(length - i - 1, 10 - used.size - 1);
+      }
+    }
+
+    if (used.has(digits[i])) break;
+    used.add(digits[i]);
+    if (i === length - 1) result++;
+  }
+
+  return n - result;
+};