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class Solution {
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 public:
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  string reformatDate(string date) {
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    // easiest way to get index with O(1)
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    unordered_map<string, string> months = {
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        {"Jan", "01"}, {"Feb", "02"}, {"Mar", "03"}, {"Apr", "04"}, {"May", "05"}, {"Jun", "06"},
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        {"Jul", "07"}, {"Aug", "08"}, {"Sep", "09"}, {"Oct", "10"}, {"Nov", "11"}, {"Dec", "12"}};
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    istringstream s(date);
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    // get day
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    string day;
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    s >> day;
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    day.pop_back();
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    day.pop_back();
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    if (day.size() == 1) day = "0" + day;
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    // get month
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    string month;
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    s >> month;
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    // get year
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    string year;
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    s >> year;
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    return year + "-" + months[month] + "-" + day;
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  }
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};