Rower Bo 题目连接: http://acm.hdu.edu.cn/showproblem.php?pid=5761 Description There is a river on the Cartesian coordinate system,the river is flowing along the x-axis direction. Rower Bo is placed at (0,a) at first.He wants to get to origin (0,0) by boa…

传送门 Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 131072/131072 K (Java/Others)Special Judge Problem DescriptionThere is a river on the Cartesian coordinate system,the river is flowing along the x-axis direction. Rower Bo is placed at $(0,a…

Rower Bo Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 131072/131072 K (Java/Others)Total Submission(s): 641    Accepted Submission(s): 199Special Judge Problem Description ,and the speed of the water flow is v2.He will adjust the direction…

题目链接: http://acm.hdu.edu.cn/showproblem.php?pid=5761 题目大意: 船在(0,a),船速v1,水速v2沿x轴正向,船头始终指向(0,0),问到达(0,0)用时,无解输出Infinity. 题目思路: [数学] 说是数学其实更像物理. 很明显v1<=v2时无解. 这道题列积分方程然后解出来式子是t=a*v1/(v12-v22). 我列积分方程的时候少了一个式子没解出来. 可以看看半根毛线的.http://images2015.cnblogs.com…

1010 Rower Bo 首先这个题微分方程强解显然是可以的,但是可以发现如果设参比较巧妙就能得到很方便的做法. 先分解v_1v​1​​, 设船到原点的距离是rr,容易列出方程 \frac{ dr}{ dt}=v_2\cos \theta-v_1​dt​​dr​​=v​2​​cosθ−v​1​​ \frac{ dx}{ dt}=v_2-v_1\cos \theta​dt​​dx​​=v​2​​−v​1​​cosθ 上下界都是清晰的,定积分一下: 0-a=v_2\int_0^T\cos\thet…

题目链接: Rower Bo Time Limit: 2000/1000 MS (Java/Others)     Memory Limit: 131072/131072 K (Java/Others) Problem Description There is a river on the Cartesian coordinate system,the river is flowing along the x-axis direction. Rower Bo is placed at (0,a)…

Rower Bo Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 131072/131072 K (Java/Others)Total Submission(s): 650    Accepted Submission(s): 203Special Judge Problem Description There is a river on the Cartesian coordinate system,the river is fl…

题目链接: http://acm.hdu.edu.cn/showproblem.php?pid=5753 题目大意: 两个序列h和c,h为1~n的乱序.h[0]=h[n+1]=0,[A]表示A为真则为1,假为0. 函数f(h)=(i=1~n)∑ci[hi>hi−1 && hi>hi+1] 现在给定c的值,求f(h)的期望. 题目思路: [数学] 头尾的概率为1/2,中间的概率为1/3,直接求和. // //by coolxxx // #include<iostream&g…

Sqrt Bo 题目链接: http://acm.hdu.edu.cn/showproblem.php?pid=5752 Description Let's define the function f(n)=⌊n−−√⌋. Bo wanted to know the minimum number y which satisfies fy(n)=1. note:f1(n)=f(n),fy(n)=f(fy−1(n)) It is a pity that Bo can only use 1 unit…

Permutation Bo 题目链接: http://acm.hdu.edu.cn/showproblem.php?pid=5753 Description There are two sequences h1∼hn and c1∼cn. h1∼hn is a permutation of 1∼n. particularly, h0=hn+1=0. We define the expression [condition] is 1 when condition is True,is 0 whe…