Add solution #424

Author: JoshCrozier

README.md

@@ -338,6 +338,7 @@
 420|[Strong Password Checker](./0420-strong-password-checker.js)|Hard|
 421|[Maximum XOR of Two Numbers in an Array](./0421-maximum-xor-of-two-numbers-in-an-array.js)|Medium|
 423|[Reconstruct Original Digits from English](./0423-reconstruct-original-digits-from-english.js)|Medium|
+424|[Longest Repeating Character Replacement](./0424-longest-repeating-character-replacement.js)|Medium|
 434|[Number of Segments in a String](./0434-number-of-segments-in-a-string.js)|Easy|
 435|[Non-overlapping Intervals](./0435-non-overlapping-intervals.js)|Medium|
 437|[Path Sum III](./0437-path-sum-iii.js)|Medium|

solutions/0424-longest-repeating-character-replacement.js

@@ -0,0 +1,32 @@
+/**
+ * 424. Longest Repeating Character Replacement
+ * https://leetcode.com/problems/longest-repeating-character-replacement/
+ * Difficulty: Medium
+ *
+ * You are given a string s and an integer k. You can choose any character of the string
+ * and change it to any other uppercase English character. You can perform this operation
+ * at most k times.
+ *
+ * Return the length of the longest substring containing the same letter you can get after
+ * performing the above operations.
+ */
+
+/**
+ * @param {string} s
+ * @param {number} k
+ * @return {number}
+ */
+var characterReplacement = function(s, k) {
+  const count = new Map();
+  let max = 0;
+  let left = 0;
+
+  return s.split('').reduce((maxLength, char, right) => {
+    count.set(char, (count.get(char) || 0) + 1);
+    max = Math.max(max, count.get(char));
+    if (right - left + 1 - max > k) {
+      count.set(s[left], count.get(s[left++]) - 1);
+    }
+    return Math.max(maxLength, right - left + 1);
+  }, 0);
+};