class Solution {
public:
int totalMoney(int n) {
// 所有完整的周存的钱
int weekNumber = n / 7;
int firstWeekMoney = (1 + 7) * 7 / 2;
int lastWeekMoney = firstWeekMoney + 7 * (weekNumber - 1);
int weekMoney = (firstWeekMoney + lastWeekMoney) * weekNumber / 2;
// 剩下的不能构成一个完整的周的天数里存的钱
int dayNumber = n % 7;
int firstDayMoney = 1 + weekNumber;
int lastDayMoney = firstDayMoney + dayNumber - 1;
int dayMoney = (firstDayMoney + lastDayMoney) * dayNumber / 2;
return weekMoney + dayMoney;
}
};
两个基本规则:
1.第二周比前周一多7；
2.计算每周的钱：首日加末日×天数除2；
