feat(problems): add LeetCode array problem solutions

work/Easy/Array/1413.minimum-value-to-get-positive-step-by-step-sum.js

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+/*
+ * 1413. Minimum Value to Get Positive Step by Step Sum
+ * Difficulty: Easy
+ * https://leetcode.com/problems/minimum-value-to-get-positive-step-by-step-sum/
+ * 
+ * ──────────────────────────────────────────────────
+ * 
+ * Given an array of integers nums, you start with an initial positive
+ * value startValue.
+ * 
+ * In each iteration, you calculate the step by step sum of startValue
+ * plus elements in nums (from left to right).
+ * 
+ * Return the minimum positive value of startValue such that the step by
+ * step sum is never less than 1.
+ * 
+ *  
+ * 
+ * Example 1:
+ * 
+ * Input: nums = [-3,2,-3,4,2]
+ * Output: 5
+ * Explanation: If you choose startValue = 4, in the third iteration
+ * your step by step sum is less than 1.
+ * step by step sum
+ * startValue = 4 | startValue = 5 | nums
+ *   (4 -3 ) = 1  | (5 -3 ) = 2    |  -3
+ *   (1 +2 ) = 3  | (2 +2 ) = 4    |   2
+ *   (3 -3 ) = 0  | (4 -3 ) = 1    |  -3
+ *   (0 +4 ) = 4  | (1 +4 ) = 5    |   4
+ *   (4 +2 ) = 6  | (5 +2 ) = 7    |   2
+ * 
+ * Example 2:
+ * 
+ * Input: nums = [1,2]
+ * Output: 1
+ * Explanation: Minimum start value should be positive. 
+ * 
+ * Example 3:
+ * 
+ * Input: nums = [1,-2,-3]
+ * Output: 5
+ * 
+ *  
+ * 
+ * Constraints:
+ * 
+ * 	• 1 <= nums.length <= 100
+ * 
+ * 	• -100 <= nums[i] <= 100
+*/
+
+/**
+ * @param {number[]} nums
+ * @return {number}
+ */
+var minStartValue = function(nums) {
+  let prefix = [nums[0]];
+  // Make prefix sum start at 1 after initializing seed value
+  for (let i = 1; i < nums.length; i++){
+    prefix.push(prefix[i - 1] + nums[i]);
+  }
+
+  let min = Math.min(...prefix);
+  return Math.max(1, 1 - min);
+};

work/Easy/Array/1480.running-sum-of-1d-array.js

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+/*
+ * 1480. Running Sum of 1d Array
+ * Difficulty: Easy
+ * https://leetcode.com/problems/running-sum-of-1d-array/
+ * 
+ * ──────────────────────────────────────────────────
+ * 
+ * Given an array nums. We define a running sum of an array as
+ * runningSum[i] = sum(nums[0]…nums[i]).
+ * 
+ * Return the running sum of nums.
+ * 
+ *  
+ * 
+ * Example 1:
+ * 
+ * Input: nums = [1,2,3,4]
+ * Output: [1,3,6,10]
+ * Explanation: Running sum is obtained as follows: [1, 1+2, 1+2+3,
+ * 1+2+3+4].
+ * 
+ * Example 2:
+ * 
+ * Input: nums = [1,1,1,1,1]
+ * Output: [1,2,3,4,5]
+ * Explanation: Running sum is obtained as follows: [1, 1+1, 1+1+1,
+ * 1+1+1+1, 1+1+1+1+1].
+ * 
+ * Example 3:
+ * 
+ * Input: nums = [3,1,2,10,1]
+ * Output: [3,4,6,16,17]
+ * 
+ *  
+ * 
+ * Constraints:
+ * 
+ * 	• 1 <= nums.length <= 1000
+ * 
+ * 	• -10^6 <= nums[i] <= 10^6
+*/
+
+/**
+ * @param {number[]} nums
+ * @return {number[]}
+ */
+var runningSum = function(nums) {
+  let prefix = [nums[0]];
+  for (let i = 1; i < nums.length; i++){
+    prefix.push(prefix[i - 1] + nums[i]);
+  }
+  return prefix;
+};

work/Medium/Array/2090.k-radius-subarray-averages.js

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+/*
+ * 2090. K Radius Subarray Averages
+ * Difficulty: Medium
+ * https://leetcode.com/problems/k-radius-subarray-averages/
+ * 
+ * ──────────────────────────────────────────────────
+ * 
+ * You are given a 0-indexed array nums of n integers, and an integer k.
+ * 
+ * The k-radius average for a subarray of nums centered at some index i
+ * with the radius k is the average of all elements in nums between the
+ * indices i - k and i + k (inclusive). If there are less than k elements
+ * before or after the index i, then the k-radius average is -1.
+ * 
+ * Build and return an array avgs of length n where avgs[i] is the
+ * k-radius average for the subarray centered at index i.
+ * 
+ * The average of x elements is the sum of the x elements divided by x,
+ * using integer division. The integer division truncates toward zero,
+ * which means losing its fractional part.
+ * 
+ * • For example, the average of four elements 2, 3, 1, and 5 is (2 + 3
+ * + 1 + 5) / 4 = 11 / 4 = 2.75, which truncates to 2.
+ * 
+ *  
+ * 
+ * Example 1:
+ * 
+ * Input: nums = [7,4,3,9,1,8,5,2,6], k = 3
+ * Output: [-1,-1,-1,5,4,4,-1,-1,-1]
+ * Explanation:
+ * - avg[0], avg[1], and avg[2] are -1 because there are less than k
+ * elements before each index.
+ * - The sum of the subarray centered at index 3 with radius 3 is: 7 + 4
+ * + 3 + 9 + 1 + 8 + 5 = 37.
+ *   Using integer division, avg[3] = 37 / 7 = 5.
+ * - For the subarray centered at index 4, avg[4] = (4 + 3 + 9 + 1 + 8 +
+ * 5 + 2) / 7 = 4.
+ * - For the subarray centered at index 5, avg[5] = (3 + 9 + 1 + 8 + 5 +
+ * 2 + 6) / 7 = 4.
+ * - avg[6], avg[7], and avg[8] are -1 because there are less than k
+ * elements after each index.
+ * 
+ * Example 2:
+ * 
+ * Input: nums = [100000], k = 0
+ * Output: [100000]
+ * Explanation:
+ * - The sum of the subarray centered at index 0 with radius 0 is:
+ * 100000.
+ *   avg[0] = 100000 / 1 = 100000.
+ * 
+ * Example 3:
+ * 
+ * Input: nums = [8], k = 100000
+ * Output: [-1]
+ * Explanation: 
+ * - avg[0] is -1 because there are less than k elements before and
+ * after index 0.
+ * 
+ *  
+ * 
+ * Constraints:
+ * 
+ * 	• n == nums.length
+ * 
+ * 	• 1 <= n <= 10^5
+ * 
+ * 	• 0 <= nums[i], k <= 10^5
+*/
+
+/**
+ * @param {number[]} nums
+ * @param {number} k
+ * @return {number[]}
+ */
+var getAverages = function(nums, k) {
+    
+};

work/Medium/Array/238.product-of-array-except-self.js

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+/*
+ * 238. Product of Array Except Self
+ * Difficulty: Medium
+ * https://leetcode.com/problems/product-of-array-except-self/
+ * 
+ * ──────────────────────────────────────────────────
+ * 
+ * Given an integer array nums, return an array answer such that
+ * answer[i] is equal to the product of all the elements of nums except
+ * nums[i].
+ * 
+ * The product of any prefix or suffix of nums is guaranteed to fit in a
+ * 32-bit integer.
+ * 
+ * You must write an algorithm that runs in O(n) time and without using
+ * the division operation.
+ * 
+ *  
+ * 
+ * Example 1:
+ * 
+ * Input: nums = [1,2,3,4]
+ * Output: [24,12,8,6]
+ * 
+ * Example 2:
+ * 
+ * Input: nums = [-1,1,0,-3,3]
+ * Output: [0,0,9,0,0]
+ * 
+ *  
+ * 
+ * Constraints:
+ * 
+ * 	• 2 <= nums.length <= 10^5
+ * 
+ * 	• -30 <= nums[i] <= 30
+ * 
+ * • The input is generated such that answer[i] is guaranteed to fit in
+ * a 32-bit integer.
+ * 
+ *  
+ * 
+ * Follow up: Can you solve the problem in O(1) extra space complexity?
+ * (The output array does not count as extra space for space complexity
+ * analysis.)
+*/
+
+/**
+ * @param {number[]} _nums
+ * @return {number[]}
+ */
+var productExceptSelf = function(_nums
+      
+};