Create 2615-sum-of-distances.js

Author: everthis

2615-sum-of-distances.js

@@ -0,0 +1,36 @@
+/**
+ * @param {number[]} nums
+ * @return {number[]}
+ */
+const distance = function(nums) {
+  const n = nums.length
+  const res = Array(n).fill(0)
+  const hash = {}
+  for(let i = 0; i < n; i++) {
+    const e = nums[i]
+    if(hash[e] == null) hash[e] = []
+    hash[e].push(i)
+  }
+  
+  const keys = Object.keys(hash)
+  for(const k of keys) {
+    const arr = hash[k]
+    const totalSum = arr.reduce((ac, e) => ac + e, 0)
+    let preSum = 0
+    if(arr.length < 2) continue
+    for(let i = 0, len =  arr.length; i < len; i++) {
+      const idx = arr[i]
+      const postSum =  totalSum - (preSum + idx)
+      
+      res[idx] += idx * i
+      res[idx] -= preSum
+      res[idx] -= idx * (len - 1 - i)
+      res[idx] += postSum
+      
+      preSum += idx
+    }
+  }
+  
+  
+  return res
+};