1+ #include < vector>
2+ #include < algorithm>
3+ #include < iostream>
4+ #include < bits/stdc++.h>
5+ using namespace std ;
6+ 7+ class Solution {
8+ public:
9+ int numberOfRounds (string startTime, string finishTime) {
10+ int startMinu = getMinutes (startTime);
11+ int endMinu = getMinutes (finishTime);
12+ if (endMinu < startMinu) endMinu += 24 * 60 ; /* case: ["20:00", "06:00"], 包括了 00:00 */
13+ else if (endMinu - startMinu < 15 ) return 0 ; /* case: ["00:47", "00:57"] */
14+ int validStart = startMinu % 15 != 0 ? (startMinu / 15 + 1 ) * 15 : startMinu / 15 * 15 ;
15+ int validEnd = endMinu / 15 * 15 ;
16+ return (validEnd - validStart) / 15 ; /* 有效区间: 原区间的子区间, 两端均收缩, 即endTime/15向下取整 - startTime/15向上取整 */
17+ }
18+ int getMinutes (string ts)
19+ {
20+ int hour = stoi (ts.substr (0 , 2 ));
21+ int minute = stoi (ts.substr (3 , 2 ));
22+ return 60 *hour + minute;
23+ }
24+ };
25+ 26+ // Test
27+ int main ()
28+ {
29+ Solution sol;
30+ string start = " 20:00"
31+ string end = " 06:00"
32+ auto res = sol.numberOfRounds (start, end);
33+ cout << res << endl;
34+ 35+ return 0 ;
36+ }
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