Microsoft Windows Internal--4th Edition,5th Edition
Windows Via C/C++
Win32 API
Structure and Interpretation of Computer Programs
The Art Of Computer Programming--1,3
Concrete Mathematics
P.S:Adding...
Friday 27 February 2009
Sunday 22 February 2009
Saturday 21 February 2009
Iron Chain Solved
I found that yesterday I forgot the theorem of kinetic energy when I was discussing this problem with CPY this morning.
Yeah,I just got an Accepted on this problem.I want to share my thoughts with all of you~~
I suppose you know that using the theorem of kinetic energy you can get the relation between velocity and displacement:
v=[2*g*x*(b-a+x)/(a+b)]^-1
P.S.:x is the displacement of one end of the iron chain.
So,we can suppose that the velocity in a VERY LITTILE displacement is increasing at a constant speed,then we can figure out the time the chain spent passing this VERY LITTLE displacement,then add the time the iron chain straightly falling down,and we will have some code like this bellow:
Then you can output the variable time as answer~
I am only a high school student in China,and I know my English isn't very well...
Hope this post useful to you,and hope you can understand my meaning..
HEHE~
Yeah,I just got an Accepted on this problem.I want to share my thoughts with all of you~~
I suppose you know that using the theorem of kinetic energy you can get the relation between velocity and displacement:
v=[2*g*x*(b-a+x)/(a+b)]^-1
P.S.:x is the displacement of one end of the iron chain.
So,we can suppose that the velocity in a VERY LITTILE displacement is increasing at a constant speed,then we can figure out the time the chain spent passing this VERY LITTLE displacement,then add the time the iron chain straightly falling down,and we will have some code like this bellow:
Then you can output the variable time as answer~
I am only a high school student in China,and I know my English isn't very well...
Hope this post useful to you,and hope you can understand my meaning..
HEHE~
Friday 20 February 2009
Iron Chain
A problem from an online judge system:
In physics class, the teacher shows us an interesting physics experiment. He hangs an iron chain on a fixed point on the wall. (Look at the right picture for more details). If the lengths of the iron chains on the left side and right side are different, the gravity forces the iron chain to drop to the floor and hits the sensor. Then the computer shows the F-t functional image on the screen. The teacher wants to teach you momentum and its conservation.
But you are not interested in this at all. The thing you want to know is how long it takes for the iron chain to drop to the floor.
You can assume that the iron chain is well-mixed, and you can ignore the friction between the iron chain and the fixed point on the wall. The friction between the chain and the air needn’t be taken into account either. The fixed point is a particle whose radius is 0. And the acceleration of gravity, or so-called g, is 9.80665m/s^2 in this problem.
Example:
1.Input: a=0 ,b=10,h=20
Output: t=1.428s
2.Input: a=1,b=3,h=4
Output: t=0.595s
============Cut-Off Rule===========
I've tried the approximation algorithm.But I couldn't pass through the judge.[I've passed the Examples before.]
And I communicated with CPY about using Calculus to solve this problem,but we couldn't solve the equation.
Who can help me....
In physics class, the teacher shows us an interesting physics experiment. He hangs an iron chain on a fixed point on the wall. (Look at the right picture for more details). If the lengths of the iron chains on the left side and right side are different, the gravity forces the iron chain to drop to the floor and hits the sensor. Then the computer shows the F-t functional image on the screen. The teacher wants to teach you momentum and its conservation.
But you are not interested in this at all. The thing you want to know is how long it takes for the iron chain to drop to the floor.
You can assume that the iron chain is well-mixed, and you can ignore the friction between the iron chain and the fixed point on the wall. The friction between the chain and the air needn’t be taken into account either. The fixed point is a particle whose radius is 0. And the acceleration of gravity, or so-called g, is 9.80665m/s^2 in this problem.
Example:
1.Input: a=0 ,b=10,h=20
Output: t=1.428s
2.Input: a=1,b=3,h=4
Output: t=0.595s
============Cut-Off Rule===========
I've tried the approximation algorithm.But I couldn't pass through the judge.[I've passed the Examples before.]
And I communicated with CPY about using Calculus to solve this problem,but we couldn't solve the equation.
Who can help me....
Wednesday 18 February 2009
Friday 6 February 2009
Rate My Life
| This Is My Life, Rated | |
| Life: |  7.4 |
| Mind: | 7.8 |
| Body: |  7.3 |
| Spirit: | 6.8 |
| Friends/Family: |  6.3 |
| Love: |  3.6 |
| Finance: |  5.5 |
| Take the Rate My Life Quiz | |
Wednesday 4 February 2009
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