Bridge over a rough river
|Time Limit: 1000MS||Memory Limit: 65536K|
|Total Submissions: 3063||Accepted: 1211|
A group of N travelers (1 ≤ N ≤ 50) has approached an old and shabby bridge and wishes to cross the river as soon as possible. However, there can be no more than two persons on the bridge at a time. Besides it's necessary to light the way with a torch for safe crossing but the group has only one torch.
Each traveler needs ti seconds to cross the river on the bridge; i=1, ... , N (ti are integers from 1 to 100). If two travelers are crossing together their crossing time is the time of the slowest traveler.
The task is to determine minimal crossing time for the whole group.
The input consists of two lines: the first line contains the value of N and the second one contains the values of ti (separated by one or several spaces).
The output contains one line with the result.
6 7 6 5
Northeastern Europe 2001, Western Subregion
Just like POJ 1700;
[sourcecode language="cpp" collapse="true" padlinenumbers="true"]
//Fri May 21 15:37:01 CDT 2010
using namespace std;
long long crossriver(vector<int> v, int T)
if (T == 1)
if (T == 2)
if (T == 3)
return v + v + v;
if (v + 3 * v + v[T - 1] > 2 * v + v + v[T - 2] + v[T - 1])
return 2 * v + v[T - 2] + v[T - 1] + crossriver(v, T - 2);
return v + 2 * v + v[T - 1] + crossriver(v, T - 2);
int main(int argc, const char* argv)
// freopen("input.in", "r", stdin);
// freopen("output.out", "w", stdout);
while(cin >> T)
for(int i=0; i<T; i++)
cin >> number;
cout << crossriver(v, T) << endl;