Last Substring in Lexicographical Order LeetCode solution in Java

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class Solution {
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  public String lastSubstring(String s) {
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    int maxIndex = s.length() - 1;
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    for (int currIndex = s.length() - 1; currIndex >= 0; currIndex--) {
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      if (s.charAt(currIndex) > s.charAt(maxIndex)) maxIndex = currIndex;
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      else if (s.charAt(currIndex) == s.charAt(maxIndex)) {
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        int i = currIndex + 1;
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        int j = maxIndex + 1;
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        while (i < maxIndex && j < s.length() && s.charAt(i) == s.charAt(j)) {
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          i++;
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          j++;
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        }
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        if (i == maxIndex || j == s.length() || s.charAt(i) > s.charAt(j)) maxIndex = currIndex;
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      }
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    }
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    return s.substring(maxIndex);
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  }
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}