11044 - Searching for Nessy
Time limit: 3.000 seconds
The Loch Ness Monsteris a mysterious and unidentified animal said to inhabit Loch Ness,
a large deep freshwater loch near the city of Inverness in northern Scotland. Nessie is usually categorized as a type of lake monster.
http://en.wikipedia.org/wiki/Loch_Ness_Monster
In July 2003, the BBC reported an extensive investigation of Loch Ness by a BBC team, using 600 separate sonar beams, found no trace of any ¨sea monster¨ (i.e., any large animal, known or unknown) in the loch. The BBC team concluded that Nessie does not exist.
Now we want to repeat the experiment.
Given a grid of n rows and m columns representing the loch, 6n, m10000,
find the minimum number s of sonar beams you must put in the square such that we can control every position in the grid, with the following conditions:
- one sonar occupies one position in the grid; the sonar beam controls its own cell and the contiguous cells;
- the border cells do not need to be controlled, because Nessy cannot hide there (she is too big).
For example,
where X represents a sonar, and the shaded cells are controlled by their sonar beams; the last figure gives us a solution.
Input
The first line of the input contains an integer, t, indicating the number of test cases. For each test case, there is a line
with two numbers separated by blanks, 6n, m10000,
that is, the size of the grid (n rows and m columns).
Output
For each test case, the output should consist of one line showing the minimum number of sonars that verifies the conditions above.
Sample Input
3 6 6 7 7 9 13
Sample Output
4 4 12
完整代码:
/*0.012s*/ #include<cstdio> #include<cmath> int main(void) { int t, n, m; scanf("%d", &t); while (t--) { scanf("%d%d", &n, &m); printf("%d\n", (int)ceil((double)(n - 2) / 3) * (int)ceil((double)(m - 2) / 3)); } return 0; }