题目：一群访客参加宴会，我们询问到每一位访客的进场时刻与出场时刻（即：已知访客的进场时刻与出场时刻），请问宴会现场挤进最多人的时段。
这个问题的关键不是访客，而是出入时刻。
1 struct Guest { int arrival; int leave; } g[7] = { { 10, 12 }, { 12, 14 }, { 12, 13 }, { 9, 15 }, {13, 15 }, { 14, 15 }, {15,15} }; 2 3 bool cmp(const int& i, const int& j) 4 { 5 return abs(i) < abs(j); 6 } 7 8 int maximum_guest() 9 {//返回宾客最多的人数 10 11 vector<int> time; 12 for (int i = 0; i<7; ++i) 13 { 14 time.push_back(+g[i].arrival); 15 time.push_back(-g[i].leave); 16 } 17 for (auto&u : time) 18 { 19 cout << u << " "; 20 } 21 sort(time.begin(), time.end(), cmp); 22 cout << endl; 23 for (auto&u : time) 24 { 25 cout << u << " "; 26 } 27 int n = 0, maximum = 0; 28 int i; 29 for ( i = 0; i<time.size(); ++i) 30 { 31 if (time[i] >= 0) 32 n++; 33 else 34 n--; 35 36 maximum = max(maximum, n); 37 } 38 39 cout<<endl << "人潮最多的時段有" << maximum << "人"; 40 41 return maximum; 42 } 43 44 void max_time() 45 {//问题主函数 46 int maximum = maximum_guest(); 47 vector<int> time; 48 for (int i = 0; i<7; ++i) 49 { 50 time.push_back(+g[i].arrival); 51 time.push_back(-g[i].leave); 52 } 53 sort(time.begin(), time.end(), cmp); 54 int n = 0; 55 int flag = 1; 56 int temp; 57 for (int i = 0; i<time.size(); ++i) 58 { 59 if (time[i] >= 0) 60 n++; 61 else 62 n--; 63 64 if (n == maximum) 65 { 66 temp = i; 67 flag = 0; 68 } 69 if (flag == 0 && n == maximum - 1) 70 { 71 cout << endl << "time:" << time[temp] << "to" << time[i]; 72 } 73 } 74 } 75 76 int main() 77 { 78 max_time(); 79 getchar(); 80 return 0; 81 }