Last Substring in Lexicographical Order LeetCode solution in C++

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class Solution {
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 public:
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  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[currIndex] > s[maxIndex])
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        maxIndex = currIndex;
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      else if (s[currIndex] == s[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[i] == s[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[i] > s[j]) maxIndex = currIndex;
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      }
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    }
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    return s.substr(maxIndex);
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  }
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};