Number of Days Between Two Dates LeetCode solution in Java

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class Solution {
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  public int daysBetweenDates(String date1, String date2) {
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    String[] d1 = date1.split("-");
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    String[] d2 = date2.split("-");
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    return (int)
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        Math.abs(
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            daysFrom1971(Integer.parseInt(d1[0]), Integer.parseInt(d1[1]), Integer.parseInt(d1[2]))
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                - daysFrom1971(
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                    Integer.parseInt(d2[0]), Integer.parseInt(d2[1]), Integer.parseInt(d2[2])));
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  }
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  private int daysFrom1971(int year, int month, int day) {
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    int total = 0;
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    // count years first
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    total += (year - 1971) * 365;
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    for (int i = 1972; i < year; i += 4) {
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      if (isLeapYear(i)) total++;
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    }
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    int feb = isLeapYear(year) ? 29 : 28;
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    // sum months and days
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    switch (month) {
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      case 12:
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        total += 30; // 11
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      case 11:
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        total += 31; // 10
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      case 10:
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        total += 30; // 9
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      case 9:
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        total += 31; // 8
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      case 8:
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        total += 31; // 7
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      case 7:
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        total += 30; // 6
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      case 6:
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        total += 31; // 5
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      case 5:
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        total += 30; // 4
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      case 4:
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        total += 31; // 3
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      case 3:
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        total += feb; // 2
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      case 2:
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        total += 31;
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      case 1:
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        total += day;
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    }
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    return total;
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  }
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  private boolean isLeapYear(int i) {
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    return (i % 4 == 0) && ((i % 100 == 0 && i % 400 == 0) || i % 100 != 0);
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  }
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}