Saving Endeavour
Time Limit:2000MS Memory Limit:65536K
Total Submit:223 Accepted:102
Description Space
shuttle Endeavour (Endeavour is of British style, and Endeavor is of
American style. Why NASA uses the British style? You can find the
answer by Baidu or Google) is in danger!
Endeavour meets the same problem as Columbus had met in 2003. When
it was sent into space, some material on the surface of the space
shuttle is damaged. When it reenters the atmosphere, hot air may
destroy the shuttle and make it fall into pieces. NASA says that the
only method to save Endeavour is to send another shuttle into space to
help repair the Endeavour. But considering the condition of other
shuttles available, such as Atlantis and Discovery, scientists think
they are not capable to complete the demanding task. NASA has to build
another new space shuttle.
There are N parts of this new shuttle need to be built. Because the
shuttle will be assembled before all parts are ready. NASA wants to
minimize the time to build all parts.
There are two workshops S1 and S2. A part must be processed by
these two workshops in order, which means that a part must be processed
first in S1 and then in S2. It is known that a workshop cannot process
more than one part simultaneously. You job is to calculate the minimum
time to build all parts.
Input For
every test block in the input, the first line contains an integer N (1
<= N <= 10000), representing the number of parts. Next follow N
lines. Each line contains two integers a and b (0 <= a, b <=
100), representing the time consumed in S1, S2 for the corresponding
part.
There is a single 0 after the last test block, and you should not process it.
Output There is only one line for one test block, namely the earliest finishing time.
Sample Input
4
1 2
3 4
5 6
7 8
4
10 1
10 1
1 10
1 10
5
4 5
4 1
30 4
6 30
2 3
6
5 7
1 2
8 2
5 4
3 7
4 4
0
Sample Output
24
23
47
28
Source POJ Monthly--2006.01.22,anonymous
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