Slid wind

Dynamic-Programming/Sliding-Window/FruitsIntoBasket.js

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+/**
+ * @function totalFruit
+ * @param {number[]} arr
+ * @return {number} res
+ * @see https://leetcode.com/problems/fruit-into-baskets/
+ * @see [sliding-window-technique] (https://www.geeksforgeeks.org/window-sliding-technique/)
+ */
+
+export const totalFruit = function (arr) {
+  // to maximize number of elements that our basket can have
+  let max = 0
+  // keeps track of the occurrence of each element
+  const hash = {}
+  // left side of the window
+  let j = 0
+  // to count number of elements
+  let objLength = 0
+
+  for (let i = 0; i < arr.length; i++) {
+    // A hashmap keeps track of each character and it's occurrence
+    if (!hash[arr[i]]) {
+      hash[arr[i]] = 1
+      // when we have a new element we increment objLength
+      objLength++
+    } else {
+      hash[arr[i]]++
+    }
+    if (objLength <= 2) {
+      // maximizing and opening the window
+      max = Math.max(max, i - j + 1)
+    } else {
+      // once we have more than two distinct elements in our hashmap, we should shrink our window
+      while (objLength > 2) {
+        hash[arr[j]]--
+        // when the occurrence of an element becomes 0 we should delete it from the hashmap
+        if (hash[arr[j]] === 0) {
+          delete hash[arr[j]]
+          objLength--
+        }
+        j++
+      }
+    }
+  }
+
+  return max
+}

Dynamic-Programming/Sliding-Window/test/FruitsIntoBasket.test.js

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+import { totalFruit } from '../FruitsIntoBasket'
+
+test('result : ', () => {
+  expect(totalFruit([3, 3, 3, 1, 2, 1, 1, 2, 3, 3, 4])).toStrictEqual(5)
+  expect(totalFruit([5, 3, 3, 1, 2])).toStrictEqual(3)
+  expect(totalFruit([9, 1, 2, 2, 2])).toStrictEqual(4)
+  expect(totalFruit([3, 3, 3])).toStrictEqual(3)
+  expect(totalFruit([])).toStrictEqual(0)
+})