Count All Possible Routes LeetCode solution in JavaScript

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var countRoutes = function (locations, start, finish, fuel) {
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  const memo = new Array(locations.length + 1)
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    .fill(0)
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    .map(() => new Array(201).fill(-1));
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  const dfs = function (cur, f) {
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    if (f < 0) return 0;
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    if (memo[cur][f] != -1) return memo[cur][f];
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    let res = cur == finish;
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    for (let i in locations) {
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      if (i == cur) continue;
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      res =
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        (res + dfs(i, f - Math.abs(locations[i] - locations[cur]))) %
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        1000000007;
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    }
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    return (memo[cur][f] = res);
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  };
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  return dfs(start, fuel);
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};