Alice 和 Bob 计划分别去罗马开会。
给你四个字符串 arriveAlice ，leaveAlice ，arriveBob 和 leaveBob 。Alice 会在日期 arriveAlice 到 leaveAlice 之间在城市里（日期为闭区间），而 Bob 在日期 arriveBob 到 leaveBob 之间在城市里（日期为闭区间）。每个字符串都包含 5 个字符，格式为 "MM-DD" ，对应着一个日期的月和日。
请你返回 Alice和 Bob 同时在罗马的天数。
你可以假设所有日期都在同一个自然年，而且不是闰年。每个月份的天数分别为：[31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31] 。
这道题的核心思想就是将当天的日期换算成是这一年的第几天，然后用天数进行运算即可，公式比较简单，如下：先走的天数-后来的天数
Python
def countDaysTogether(
arriveAlice: str, leaveAlice: str, arriveBob: str, leaveBob: str
) -> int:
datesOfMonths = [31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31]
prefixSum = [0]
for date in datesOfMonths:
# prefixSum[-1]代表引用列表最后一个元素
prefixSum.append(prefixSum[-1] + date)
arriveAliceDay = calculateDayOfYear(arriveAlice, prefixSum)
leaveAliceDay = calculateDayOfYear(leaveAlice, prefixSum)
arriveBobDay = calculateDayOfYear(arriveBob, prefixSum)
leaveBobDay = calculateDayOfYear(leaveBob, prefixSum)
# 返回0和相差日期的最大值，省去if比较
return max(
0, min(leaveAliceDay, leaveBobDay) - max(arriveAliceDay, arriveBobDay) + 1
)
def calculateDayOfYear(day: str, prefixSum: list[int]) -> int:
month = int(day[:2]) # 前两位，即月份
date = int(day[-2:]) # 后两位，即日期
return prefixSum[month - 1] + date
arriveAlice = "08-15"
leaveAlice = "08-18"
arriveBob = "08-16"
leaveBob = "08-19"
print(countDaysTogether(arriveAlice, leaveAlice, arriveBob, leaveBob))
C语言
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
// 注意宏定义的时候是直接替换文字，所以要注意括号问题
#define max(x, y) ((x) > (y) ? (x) : (y))
#define min(x, y) ((x) < (y) ? (x) : (y))
// 计算过程中一定要注意数组和数组之间的对应关系，比如7月份是过去了6个月
int days(char *date, int *presum) {
int month = (date[0] - '0') * 10 + (date[1] - '0');
int dates = (date[3] - '0') * 10 + (date[4] - '0');
return presum[month - 1] + dates;
}
int countDaysTogether(char *arriveAlice, char *leaveAlice, char *arriveBob, char *leaveBob) {
int dates[] = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
int presum[13] = {0};
for (int i = 1; i < 13; i++) {
presum[i] = dates[i - 1] + presum[i - 1];
}
int arriveAliceDay = days(arriveAlice, presum);
int leaveAliceDay = days(leaveAlice, presum);
int arriveBobDay = days(arriveBob, presum);
int leaveBobDay = days(leaveBob, presum);
int day = (min(leaveAliceDay, leaveBobDay) - max(arriveAliceDay, arriveBobDay) + 1);
return max(0, day);
}
int main() {
char *arriveAlice = "10-01", *leaveAlice = "10-31", *arriveBob = "11-01", *leaveBob = "12-31";
int day = countDaysTogether(arriveAlice, leaveAlice, arriveBob, leaveBob);
printf("两个人相聚的天数为：%d\n", day);
}
