Evaluate Division LeetCode solution in Java

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class Solution {
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  public double[] calcEquation(
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      List<List<String>> equations, double[] values, List<List<String>> queries) {
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    int len = equations.size();
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    Map<String, Integer> varMap = new HashMap<>();
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    int varCnt = 0;
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    for (int i = 0; i < len; i++) {
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      if (!varMap.containsKey(equations.get(i).get(0))) {
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        varMap.put(equations.get(i).get(0), varCnt++);
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      }
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      if (!varMap.containsKey(equations.get(i).get(1))) {
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        varMap.put(equations.get(i).get(1), varCnt++);
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      }
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    }
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    List<Pair>[] edges = new List[varCnt];
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    for (int i = 0; i < varCnt; i++) {
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      edges[i] = new ArrayList<>();
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    }
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    for (int i = 0; i < len; i++) {
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      int va = varMap.get(equations.get(i).get(0));
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      int vb = varMap.get(equations.get(i).get(1));
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      edges[va].add(new Pair(vb, values[i]));
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      edges[vb].add(new Pair(va, 1.0 / values[i]));
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    }
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    int queriesCnt = queries.size();
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    double[] ans = new double[queriesCnt];
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    for (int i = 0; i < queriesCnt; i++) {
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      List<String> query = queries.get(i);
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      double result = -1.0;
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      if (varMap.containsKey(query.get(0)) && varMap.containsKey(query.get(1))) {
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        int idxA = varMap.get(query.get(0));
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        int idxB = varMap.get(query.get(1));
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        if (idxA == idxB) {
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          result = 1.0;
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        } else {
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          Queue<Integer> points = new LinkedList<>();
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          points.offer(idxA);
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          double[] ratios = new double[varCnt];
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          Arrays.fill(ratios, -1.0);
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          ratios[idxA] = 1.0;
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          while (!points.isEmpty() && ratios[idxB] < 0) {
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            int cur = points.poll();
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            for (Pair pair : edges[cur]) {
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              int y = pair.index;
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              double value = pair.value;
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              if (ratios[y] < 0) {
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                ratios[y] = ratios[cur] * value;
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                points.offer(y);
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              }
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            }
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          }
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          result = ratios[idxB];
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        }
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      }
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      ans[i] = result;
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    }
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    return ans;
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  }
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  class Pair {
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    int index;
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    double value;
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    public Pair(int index, double value) {
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      this.index = index;
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      this.value = value;
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    }
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  }
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}