[USACO13JAN] Painting the Fence S

Farmer John has devised a brilliant method to paint the long fence next to his barn (think of the fence as a one-dimensional number line). He simply attaches a paint brush to his favorite cow Bessie, and then retires to drink a cold glass of water as Bessie walks back and forth across the fence, applying paint to any segment of the fence that she walks past. Bessie starts at position 0 on the fence and follows a sequence of N moves (1 <= N <= 100,000). Example moves might be "10 L", meaning Bessie moves 10 units to the left, or "15 R", meaning Bessie moves 15 units to the right. Given a list of all of Bessie's moves, FJ would like to know what area of the fence gets painted with at least K coats of paint. Bessie will move at most 1,000,000,000 units away from the origin during her walk. Farmer John 想出了一个给牛棚旁的长围墙涂色的好方法。（为了简单起见，我们把围墙看做一维的数轴，每一个单位长度代表一块栅栏） 他只是简单的把刷子蘸满颜料，系在他最喜欢的奶牛Bessie上，然后让Bessie来回地经过围墙，自己则在一旁喝一杯冰镇的凉水。（……-\_-|||) Bessie 经过的所有围墙都会被涂上一层颜料。Bessie从围墙上的位置0出发，并将会进行N次移动(1 <= N <= 100,000)。比如说，“10 L”的意思就是Bessie向左移动了10个单位。再比如说“15 R”的意思就是Bessie向右移动了15个单位。 给出一系列Bessie移动的清单。FJ 想知道有多少块栅栏涂上了至少K层涂料。注意：Bessie最多会移动到离原点1,000,000,000单位远的地方。

\* 第1行： 两个整数： N K \* 第2...N+1 行： 每一行都描述了Bessie的一次移动。 （比如说 “15 L"）

\* 一个整数：被至少涂上K层涂料的栅栏数 （注意：输出的最后一定要输出换行符！否则会WA）

6 2 
2 R 
6 L 
1 R 
8 L 
1 R 
2 R 

6

PS1：来源：usaco jan silver P01 想看原题的请戳http://www.usaco.org/index.php?page=viewproblem2&cpid=226） PS2：测试数据也可以在在http://www.usaco.org/index.php?page=jan13problems上下载，还可以看到题解（不过是英文的:-D） PS3:如果有翻译的问题或题目的不理解，可以在问答后面留言的说。