day of the year.cpp

// Runtime: 4 ms, faster than 57.01% of C++ online submissions for Day of the Year.
// Memory Usage: 8.5 MB, less than 100.00% of C++ online submissions for Day of the Year.

#include <iostream>
#include <string>
#include <vector>
#include <stack>

using namespace std;

class Solution
{
public:
    std::vector<std::string> string_split(std::string str, std::string delimiter)
    {
        size_t pos = 0;
        std::string token;
        std::vector<std::string> result;
        while ((pos = str.find(delimiter)) != std::string::npos)
        {
            token = str.substr(0, pos);
            result.push_back(token);
            str.erase(0, pos + delimiter.length());
        }
        result.push_back(str);
        return result;
    }

    int dayOfYear(string date)
    {
        vector<string> vs = string_split(date, "-");
        vector<int> ymd;
        int ans;

        std::transform(vs.begin(), vs.end(), std::back_inserter(ymd),
                       [](const std::string &s)
                       { return std::stoi(s); });

        ans = ymd[2]; // d

        for (int m = 1; m < ymd[1]; m++)
        {
            if (m == 2)
            {
                ans += 28;
                if (ymd[0] % 400 == 0)
                {
                    ans += 1;
                }
                else if (ymd[0] % 100 == 0)
                {
                    // 100's multiple, not 400's multiple
                    // is not leap year
                }
                else if (ymd[0] % 4 == 0)
                {
                    ans += 1;
                }
            }
            else if (m < 8)
            {
                if (m % 2 == 1)
                    ans += 31;
                else
                    ans += 30;
            }
            else
            {
                if (m % 2 == 1)
                    ans += 30;
                else
                    ans += 31;
            }
        }

        return ans;
    }
};