1701. Average Waiting Time.java

class Solution {
  public double averageWaitingTime(int[][] customers) {
    double wait = 0;
    double curr = 0;

    for (int[] c : customers) {
      curr = Math.max(curr, 1.0 * c[0]) + c[1];
      wait += curr - c[0];
    }

    return 1.0 * wait / customers.length;
  }
}