极其幸运地，我压线进入了省队，从而第一次踏上NOI的征程。
NOI2010的题有点水，不像往年单纯把题目描述看懂就要费一番周折。第一题暴力居然可以过80分的数据，恐怕和机器比较好有直接关系。这直接导致今年的分数线比往年高出100分左右。
由于是第一次NOI，对比赛还不熟，加上刚从南方培训完毕北上使得咽炎突发，直接导致两试状态都不太好。第一试最后一题网络流Dinic写挂直接导致10分（n比较小时的枚举，考试结束前5分钟加上的）。但第二试103分算是出乎我意料。最后倒也顺利拿到了铜牌。如果那道网络流写对不就银牌了么，我遗憾地想。（提醒：网络流不是那道题的标准做法，但可以获得50到100不等的分数）
讲题大会幻灯片我暂时没有，以后找到会发上来。先极其简练地说下解题思路
第一试第一题可以用公式：(0,0)到(x,y)上整点的数目是gcd(x,y)-1（不含端点），然后就可以暴力（80）或正常地枚举因数（90-100）抑或像讲题大会上某神牛使用莫比乌斯反演来恶搞一下
第二题可以用二分的思想，具体没太明白就不班门弄斧了。陈丹琦出的题就是鹤立鸡群...
第三题可以证明所有点的高度只能是0或1，这样就成了赤裸裸的最小割。因为是平面图，可以使用最短路，具体请参见某WC论文。
第二试第一题第一问比较容易构造，我用了差分约束系统不知道对不对。第二问没太理解标准做法。
第二题搜索+连通性剪枝可以拿到不错的分数，标准做法是状压动规——但考场上没人写出来。
第三题分析数据特点，有四个点可以DP，剩下的点可以贪心+随机搞定。贪心的估价可以用重量/距离，据说把距离三次方效果较好（因为距离远相对更加不合算）
每个人都享有自由，承担不侵犯别人自由的义务，试图侵犯别人的自由的卫道士，无论自己承认与否，无论多么道貌岸然，都是披着羊皮的狼。
I forgot this day! disaster...
Spent almost the whole day en route. Princeton has a really big campus and good architecture. Walking through makes me feel like England or some other European country.
Philadelphia, one of the largest cities in the US, played an important part in Independence War. The continental congress published important political documents here, like Declaration of Independence. The constitution was drafted here too. Liberty Bell inspired people to fight for freedom and justice in Civil War.
Nothing much...
春晚招人骂的本质原因是，它承载了本不应该由它承载的东西。
Sorry, but the text stored on my iPhone was gone when restoring firmware. Trying to recover. Text will come soon.
Washington D.C. is designed specifically as the nation's capital. Hence, most attractions here are political. We visited the very famous places that are very close to each other.
When we visited the Korean War memorial, some students said they wanted to destroy it. Although being a Chinese, I was deeply moved by the words "Our country honors her sons and daughters who answer her call to defend a country they never knew and people they never met". Anyway, those soldiers have done nothing wrong. They did what they should do as citizens. Whether how do we think of the war, we should respect those brave men & women. It also applies to the Vietiam war. I was shocked and moved when see the list of names. I know behind the names are lives and sorrow families.
National World War II Memorial, located north to the Vietnam Memorial, is the major memorial dedicated to those who fought bravely for the liberation of countries invaded by the Axis powers. We should thank them for their kind help and donation during the Sino-Japan War. Yes, freedom is never free.
When George Washington was alive, he never wanted people to build something for him. But American people would never forget this president who gave the nation a new birth. Washington Monument was built in memory of him. The construction was interrupted by the Civil War. So you can see the upper part of the structure was different.
Jefferson is another famous president, known as the writer of Declaration of Independence. Jefferson Memorial looks quite like Lincoln Memorial. Marble structure, huge statue, and...souvenir shop. I bought a copy of Declaration of Independence and some other famous documents.
The White House is where the president lives. The road in front of it used to open to the public. Is a inside visit possible? Depends on your luck~
Washington D.C. has lots of museums. National Air and Space Museum is among the most famous ones. There you can see many planes hanging on the roof.
Check the pictures~
Finally we see a American-like city. By saying this, I mean that we thought the united states is a country where skyscrapers are everywhere. Actually, this only happens in New York.
New York is the largest city in America. It is the economical, financial and cultural center of the United States, even the Earth. It is always regarded as an international city along with London and Paris. Take a look at Wall Street, the financial heart that drives the country.
Before visiting Wall Street, we took a boat tour to the Statue of Liberty. It used to be the first thing new immigrants see when they arrive in the New World. It is located on an isolated island - you can arrive there by boat only.
What's that building like Triumphal Arch? New York University. We didn't stay there long because of time.
In the afternoon we visited the headquarter of the United Nations. We were able to visit the Security Council and several exhibitions.
The beautiful and elegant campus is Columbia University's.
Attention, Apple fans! See the Apple Store? That's 5th Ave. I visited Central Park alone. But it's winter, so the scenery was not nice.
At night we visited the Times Square. Only there can you see so many big screens. But don't imagine how big it is - it's only a junction!
Photos...here.
Eastern United States looks like a new country if you traveled from the West. Its pace is much faster. You can know his by seeing lots of clocks everywhere.
Boston doesn't have many attractions. We went there all for the city nearby - Cambridge City, where Harvard and MIT located.
Harvard and MIT are very famous universities. But neither of them is big and modern. MIT has some modern buildings, though. Harvard is always regarded as a top university, ranking the first in the US. I went to visit the place which I have dreamed of, department of computer science of MIT. The building has a unique design. You can see the photo below.
In contrast, Yale is big and beautiful.
Feb 25
In our teacher's words, Hollywood is like Wangfujing in a way. It is something that you really need to visit. But when you arrive there, you'll soon notice that there's nothing to see. What you can see there? Well, stars, Hollywood sign, expensive shops, nothing more. You can simply take a look at Google Street View, and that's fine.
The name of the street is Hollywood Blvd. Just search for Hollywood Blvd, Hollywood, CA.
Feb 26
I don't know why don't we visit UCLA. Instead, we went to USC - University of Southern California. Just another American private university. But its medical department is pretty nice.
Feb 15
Pasadena is just a city, but with some old American styled house. All what we have done is just walking down the main road - Colorado St. and do some shopping. I stayed almost the whole afternoon in the Barnes & Noble bookstore, but finally bought books at amazon.com, where I can get half the price.
Feb 16
Huntington Beach is a major beach in California. Hearing the name, you must think it's a small place. Actually, it is the name of a city. It has all the feature that a beach has, plus, nothing more. The water is pretty cold, may not be suitable for swimming, but is perfectly fine for surfing.
Photos are here (visitor: come on! so few!)
Feb 13
For those who want to visit Disneyland, you have to understand one thing: it's just an amusement part, just with a theme. So what you get is just roller coasters and water rides.
Then why Disneyland attracts many visitors every year? It is because the theme. Although roller coasters are common, you may not see roller coasters that drives through the space, that flies across the mountain, that you can shoot targets in.
Weekends may not be a good time to visit because there is always a lot of people. The queue can be very long, and you have to wait for as long as 90 minutes. But you can get a fastpass or, if you're alone, take the single rider's queue.
Feb 14
Once upon a time, early movie companies began to move to California. It was because the sunshine here was bright & long enough. Since then, Hollywood has became the symbol of U.S. movie industry. Universal Studios, located in Universal City, CA, is the second oldest movie company in the world.
Of course, what we went to is a theme park opened by Universal Studios. But in the studio tour you can visit many stages where movies were made, and you can also see how those special effects were created.
If you want to visit this park, I strongly advise that you visit the studio tour first. It has Mandarin version available.
Here come the photos.
