HDU 3853 LOOPS (概率DP)
http://acm.hdu.edu.cn/showproblem.php?pid=3853令dp[i][j]表示从(i,j)到(R,C)花费的魔力值的期望。那么，我们有：dp[i][j] = 2 + ploop[i][j]*dp[i][j] + pleft[i][j]*dp[i][j+1] + pdown[i][j]*dp[i+1][j]移项可得：if (ploo
