solve 2 ways

algorithms/leet-code/explore/arrays-101/height-checker.js

@@ -0,0 +1,35 @@
+/**
+ * @param {number[]} heights
+ * @return {number}
+ */
+
+function merge(node1, node2) {
+    const result = [];
+    while (node1.length > 0 && node2.length > 0) {
+        if (node1[0] < node2[0]) {
+            result.push(node1.shift());
+        } else {
+            result.push(node2.shift());
+        }
+    }
+    return result.concat(node1.length ? node1 : node2);
+}
+
+function mergeSort(arr) {
+    //base case
+    if (arr.length <= 1) return arr;
+
+    const middle = Math.floor(arr.length / 2); // get the middle item of the array rounded down
+    const left = arr.slice(0, middle); // items on the left side
+    const right = arr.slice(middle); // items on the right side
+
+    return merge(mergeSort(left), mergeSort(right));
+}
+
+const heightChecker = function (heights) {
+    let moveCnt = 0;
+    mergeSort(heights).forEach((height, idx) => {
+        if (height !== heights[idx]) moveCnt++;
+    });
+    return moveCnt;
+};

algorithms/leet-code/explore/arrays-101/rotate-array.js

@@ -0,0 +1,38 @@
+// /**
+//  * @param {number[]} nums
+//  * @param {number} k
+//  * @return {void} Do not return anything, modify nums in-place instead.
+//  */
+// const rotate = function (nums, k) {
+//     //base case
+//     if (k === 0) return nums;
+
+//     while (k) {
+//         nums.unshift(nums.pop());
+//         k--;
+//     }
+// };
+
+/**
+ * @param {number[]} nums
+ * @param {number} k
+ * @return {void} Do not return anything, modify nums in-place instead.
+ */
+const rotate = function (nums, k) {
+    //base case
+    if (k === 0) return nums;
+
+    //if rotation num exceeds array length offset by array length
+    const rotations = k > nums.length ? k - nums.length : k;
+
+    // 3 steps
+
+    // reverse entire array
+    nums.reverse();
+
+    //now reverse the numbers up until the rotation number (0 to k)
+    nums.unshift(...nums.splice(0, rotations).reverse());
+
+    //now reverse k to n
+    nums.push(...nums.splice(rotations, nums.length - 1).reverse());
+};