Best Position for a Service Centre LeetCode solution in Java

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class Solution {
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  private static final double MIN_STEP = 0.0000001;
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  private static final int[][] DIRECTIONS = {{-1, 0}, {1, 0}, {0, -1}, {0, 1}};
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  public double getMinDistSum(int[][] positions) {
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    double cx = 0, cy = 0;
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    int n = positions.length;
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    for (int[] pos : positions) {
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      cx += pos[0];
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      cy += pos[1];
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    }
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    cx /= n;
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    cy /= n;
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    Node center = new Node(cx, cy, totalDistance(positions, cx, cy));
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    double step = 50.0;
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    while (step > MIN_STEP) {
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      Node min = center;
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      for (int[] direction : DIRECTIONS) {
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        double dx = center.x + direction[0] * step, dy = center.y + direction[1] * step;
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        double totalDist = totalDistance(positions, dx, dy);
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        if (totalDist < center.dist) min = new Node(dx, dy, totalDist);
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      }
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      if (center == min) step /= 2;
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      center = min;
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    }
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    return center.dist;
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  }
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  private double sq(double p) {
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    return p * p;
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  }
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  private double dist(int[] pos, double x, double y) {
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    return Math.sqrt(sq(x - pos[0]) + sq(y - pos[1]));
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  }
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  private double totalDistance(int[][] positions, double x, double y) {
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    double dist = 0;
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    for (int[] pos : positions) dist += dist(pos, x, y);
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    return dist;
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  }
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  private static class Node {
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    double x, y, dist;
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    Node(double x, double y, double dist) {
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      this.x = x;
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      this.y = y;
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      this.dist = dist;
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    }
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  }
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}