Add solution #2615

Author: JoshCrozier

README.md

@@ -1,4 +1,4 @@
-# 1,759 LeetCode solutions in JavaScript
+# 1,760 LeetCode solutions in JavaScript
 
 [https://leetcodejavascript.com](https://leetcodejavascript.com)
 
@@ -1680,6 +1680,7 @@
 2570|[Merge Two 2D Arrays by Summing Values](./solutions/2570-merge-two-2d-arrays-by-summing-values.js)|Easy|
 2579|[Count Total Number of Colored Cells](./solutions/2579-count-total-number-of-colored-cells.js)|Medium|
 2594|[Minimum Time to Repair Cars](./solutions/2594-minimum-time-to-repair-cars.js)|Medium|
+2615|[Sum of Distances](./solutions/2615-sum-of-distances.js)|Medium|
 2618|[Check if Object Instance of Class](./solutions/2618-check-if-object-instance-of-class.js)|Medium|
 2619|[Array Prototype Last](./solutions/2619-array-prototype-last.js)|Easy|
 2620|[Counter](./solutions/2620-counter.js)|Easy|

solutions/2615-sum-of-distances.js

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+/**
+ * 2615. Sum of Distances
+ * https://leetcode.com/problems/sum-of-distances/
+ * Difficulty: Medium
+ *
+ * You are given a 0-indexed integer array nums. There exists an array arr of length nums.length,
+ * where arr[i] is the sum of |i - j| over all j such that nums[j] == nums[i] and j != i. If there
+ * is no such j, set arr[i] to be 0.
+ *
+ * Return the array arr.
+ */
+
+/**
+ * @param {number[]} nums
+ * @return {number[]}
+ */
+var distance = function(nums) {
+  const valueIndices = new Map();
+  const result = new Array(nums.length).fill(0);
+
+  for (let i = 0; i < nums.length; i++) {
+    if (!valueIndices.has(nums[i])) {
+      valueIndices.set(nums[i], []);
+    }
+    valueIndices.get(nums[i]).push(i);
+  }
+
+  for (const indices of valueIndices.values()) {
+    let prefixSum = 0;
+    for (let i = 1; i < indices.length; i++) {
+      prefixSum += indices[i] - indices[0];
+    }
+
+    result[indices[0]] = prefixSum;
+
+    for (let i = 1; i < indices.length; i++) {
+      const diff = indices[i] - indices[i - 1];
+      prefixSum += diff * (i - (indices.length - i));
+      result[indices[i]] = prefixSum;
+    }
+  }
+
+  return result;
+};