Add solution #2999

Author: JoshCrozier

README.md

@@ -1,4 +1,4 @@
-# 1,225 LeetCode solutions in JavaScript
+# 1,226 LeetCode solutions in JavaScript
 
 [https://leetcodejavascript.com](https://leetcodejavascript.com)
 
@@ -1206,6 +1206,7 @@
 2874|[Maximum Value of an Ordered Triplet II](./solutions/2874-maximum-value-of-an-ordered-triplet-ii.js)|Medium|
 2948|[Make Lexicographically Smallest Array by Swapping Elements](./solutions/2948-make-lexicographically-smallest-array-by-swapping-elements.js)|Medium|
 2965|[Find Missing and Repeated Values](./solutions/2965-find-missing-and-repeated-values.js)|Easy|
+2999|[Count the Number of Powerful Integers](./solutions/2999-count-the-number-of-powerful-integers.js)|Hard|
 3042|[Count Prefix and Suffix Pairs I](./solutions/3042-count-prefix-and-suffix-pairs-i.js)|Easy|
 3066|[Minimum Operations to Exceed Threshold Value II](./solutions/3066-minimum-operations-to-exceed-threshold-value-ii.js)|Medium|
 3105|[Longest Strictly Increasing or Strictly Decreasing Subarray](./solutions/3105-longest-strictly-increasing-or-strictly-decreasing-subarray.js)|Easy|

solutions/2999-count-the-number-of-powerful-integers.js

@@ -0,0 +1,64 @@
+/**
+ * 2999. Count the Number of Powerful Integers
+ * https://leetcode.com/problems/count-the-number-of-powerful-integers/
+ * Difficulty: Hard
+ *
+ * You are given three integers start, finish, and limit. You are also given a 0-indexed string
+ * s representing a positive integer.
+ *
+ * A positive integer x is called powerful if it ends with s (in other words, s is a suffix of x)
+ * and each digit in x is at most limit.
+ *
+ * Return the total number of powerful integers in the range [start..finish].
+ *
+ * A string x is a suffix of a string y if and only if x is a substring of y that starts from
+ * some index (including 0) in y and extends to the index y.length - 1. For example, 25 is a
+ * suffix of 5125 whereas 512 is not.
+ */
+
+/**
+ * @param {number} start
+ * @param {number} finish
+ * @param {number} limit
+ * @param {string} suffix
+ * @return {number}
+ */
+var numberOfPowerfulInt = function(start, finish, limit, suffix) {
+  start--;
+  const startCount = countValidNums(start, limit, suffix);
+  const finishCount = countValidNums(finish, limit, suffix);
+  return finishCount - startCount;
+
+  function countValidNums(number, maxDigit, suffix) {
+    const suffixNum = parseInt(suffix);
+    const suffixMod = 10 ** suffix.length;
+    const suffixPart = number % suffixMod;
+    let baseNum = Math.floor(number / suffixMod);
+    if (suffixPart < suffixNum) baseNum--;
+
+    if (baseNum <= 0) return baseNum + 1;
+
+    const digitStr = baseNum.toString();
+    let count = digitStr.charCodeAt(0) - 48;
+    let isExact = 1;
+
+    if (count > maxDigit) {
+      return (maxDigit + 1) ** digitStr.length;
+    }
+
+    for (let i = 1; i < digitStr.length; i++) {
+      count *= (maxDigit + 1);
+      if (isExact) {
+        const currentDigit = digitStr.charCodeAt(i) - 48;
+        if (currentDigit > maxDigit) {
+          isExact = 0;
+          count += maxDigit + 1;
+        } else {
+          count += currentDigit;
+        }
+      }
+    }
+
+    return count + isExact;
+  }
+};