Create 0978-longest-turbulent-subarray.js

Author: aadil42

javascript/0978-longest-turbulent-subarray.js

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+/**
+ * Two Pointers | Greedy
+ * Time O(n) | Space O(1)
+ * https://leetcode.com/problems/longest-turbulent-subarray/
+ * @param {number[]} arr
+ * @return {number}
+ */
+var maxTurbulenceSize = function(arr) {
+    
+    const higherAndLower = (start) => {
+
+        let i = start;
+        let shouldBeLow = true;
+
+        while(i + 1 < arr.length) {
+            if(shouldBeLow && arr[i+1] > arr[i]) break;
+            if(!shouldBeLow && arr[i+1] < arr[i]) break;
+            if(arr[i+1] === arr[i]) break;
+            shouldBeLow = !shouldBeLow;
+            i++;
+        }
+
+        return i;
+
+    }
+
+    const lowerAndHigher = (start) => {
+
+
+        let i = start;
+        let shouldBeHigh = true;
+
+        while(i + 1 < arr.length) {
+            if(shouldBeHigh && arr[i+1] < arr[i]) break;
+            if(!shouldBeHigh && arr[i+1] > arr[i]) break;
+            if(arr[i+1] === arr[i]) break;
+            shouldBeHigh = !shouldBeHigh;
+            i++;
+        }
+
+        return i;
+    }
+
+
+    let left = 0;
+    let right = 1;
+    let max = 1;
+
+    while(right < arr.length) {
+
+        if(arr[left] > arr[right]) {
+            right = higherAndLower(left);
+            max = Math.max(right-left+1, max);
+            left = right;
+            right = right+1;
+            continue;
+        }
+
+        if(arr[left] < arr[right]) {
+            right = lowerAndHigher(left);
+            max = Math.max(right-left+1, max);
+            left = right;
+            right = right+1;
+            continue;
+        }
+
+        if(arr[left] === arr[right]) {
+            left++;
+            right++;
+        }
+
+    }
+
+    return max;
+};