Add solution #80

Author: JoshCrozier

README.md

@@ -61,6 +61,7 @@
 74|[Search a 2D Matrix](./0074-search-a-2d-matrix.js)|Medium|
 77|[Combinations](./0077-combinations.js)|Medium|
 78|[Subsets](./0078-subsets.js)|Medium|
+80|[Remove Duplicates from Sorted Array II](./0080-remove-duplicates-from-sorted-array-ii.js)|Medium|
 83|[Remove Duplicates from Sorted List](./0083-remove-duplicates-from-sorted-list.js)|Easy|
 88|[Merge Sorted Array](./0088-merge-sorted-array.js)|Easy|
 90|[Subsets II](./0090-subsets-ii.js)|Medium|

solutions/0080-remove-duplicates-from-sorted-array-ii.js

@@ -0,0 +1,36 @@
+/**
+ * 80. Remove Duplicates from Sorted Array II
+ * https://leetcode.com/problems/remove-duplicates-from-sorted-array-ii/
+ * Difficulty: Medium
+ *
+ * Given an integer array nums sorted in non-decreasing order, remove some duplicates in-place such
+ * that each unique element appears at most twice. The relative order of the elements should be kept
+ * the same.
+ *
+ * Since it is impossible to change the length of the array in some languages, you must instead have
+ * the result be placed in the first part of the array nums. More formally, if there are k elements
+ * after removing the duplicates, then the first k elements of nums should hold the final result.
+ * It does not matter what you leave beyond the first k elements.
+ *
+ * Return k after placing the final result in the first k slots of nums.
+ *
+ * Do not allocate extra space for another array. You must do this by modifying the input array
+ * in-place with O(1) extra memory.
+ */
+
+/**
+ * @param {number[]} nums
+ * @return {number}
+ */
+var removeDuplicates = function(nums) {
+  let offset = 2;
+
+  for (let i = 2; i < nums.length; i++) {
+    if (nums[i] !== nums[offset - 2]) {
+      nums[offset] = nums[i];
+      offset++;
+    }
+  }
+
+  return offset;
+};