Largest Sum of Averages LeetCode solution in JavaScript

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/**
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 * @param {number[]} nums
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 * @param {number} k
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 * @return {number}
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 */
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var largestSumOfAverages = function (nums, k) {
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  // set length
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  const len = nums.length;
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  // set sum by len fill
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  const sum = new Array(len).fill(0);
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  // set nums first to first of sum
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  sum[0] = nums[0];
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  // set every item of sum to the sum of the previous and the corresponding item of nums
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  for (let i = 1; i < len; i++) {
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    sum[i] = sum[i - 1] + nums[i];
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  }
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  // set dynamic programming
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  const dp = new Array(k + 1).fill("").map(() => new Array(len).fill(0));
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  // according to the meaning of the problem, set the value of dp
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  for (let i = 0; i < len; i++) {
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    dp[1][i] = sum[i] / (i + 1);
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  }
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  for (let i = 1; i <= k; i++) {
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    dp[i][i - 1] = sum[i - 1];
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  }
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  for (let i = 2; i <= k; i++) {
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    for (let j = i; j < len; j++) {
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      for (let m = j - 1; m >= i - 2; m--) {
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        dp[i][j] = Math.max(
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          dp[i][j],
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          dp[i - 1][m] + (sum[j] - sum[m]) / (j - m)
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        );
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      }
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    }
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  }
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  // result
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  return dp[k][len - 1];
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};