Add: Exercise 643. Max Average Subarray I

Author: BlackBeast593

643-maximum-average-subarray-1/README.md

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+# 643. Maximum Average Subarray I
+You are given an integer array `nums` consisting of `n` elements, and an integer `k`.
+
+Find a contiguous subarray whose length is equal to `k` that has the maximum average value and 
+return this value. Any answer with a calculation error less than 10^-5 will be accepted.
+
+## Examples
+
+### Example 1:
+
+Input: `nums` = [1,12,-5,-6,50,3], `k` = 4  
+Output: 12.75000  
+Explanation: Maximum average is (12 - 5 - 6 + 50) / 4 = 51 / 4 = 12.75
+
+### Example 2:
+
+Input: `nums` = [5], `k` = 1  
+Output: 5.00000
+
+## Constraints
+
+- `n == nums.length`
+- `1 <= k <= n <= 10^5`
+- `-10^4 <= nums[i] <= 10^4`

643-maximum-average-subarray-1/index.js

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+/**
+ * @param {number[]} nums
+ * @param {number} k
+ * @return {number}
+ */
+var findMaxAverage = function(nums, k) {
+    // Sliding window approach
+    let sum = 0
+    let maxAv = 0
+
+    // Calculate the initial sum
+    for (let i = 0; i < k; i++) {
+        sum += nums[i]
+    }
+
+    maxAv = sum / k
+
+    // Now let's slide the window
+    for (let i = k; i < nums.length; i++) {
+        sum = sum - nums[i-k] + nums[i]
+        const a = sum / k
+        if (a > maxAv) maxAv = a
+    }
+
+    return maxAv
+};
+
+// Use example
+var av = findMaxAverage([1,12,-5,-6,50,3], 4)
+
+module.exports = findMaxAverage

643-maximum-average-subarray-1/package.json

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+{
+  "name": "643-maximum-average-subarray-1",
+  "version": "1.0.0",
+  "description": "",
+  "main": "index.js",
+  "scripts": {
+    "start": "node index.js",
+    "debug": "node --inspect-brk index.js",
+    "test": "node test.js"
+  },
+  "keywords": [],
+  "author": "",
+  "license": "ISC"
+}

643-maximum-average-subarray-1/test.js

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+const assert = require('assert')
+const findMaxAverage = require('./index')
+
+const tests = [
+    {
+        nums: [1,12,-5,-6,50,3],
+        k: 4,
+        expectedMaxAv: 12.75,
+    },
+    {
+        nums: [5],
+        k: 1,
+        expectedMaxAv: 5,
+    },
+]
+
+for (const t of tests) {
+    assert.strict.deepEqual(findMaxAverage(t.nums, t.k), t.expectedMaxAv)
+}