15148번 - Front Nine 스페셜 저지다국어

문제

Andrew is building a 2D golf course called the Front Nine where each hole will be exactly n units long. In order to generate many (hopefully) unique holes, he will do it with a randomised algorithm. A single hole is defined by a function y : [0, n] → [0, h] which for each x-coordinate in the range [0, n] gives the height of the hole’s terrain (between 0 and h) at that point.

Andrew’s randomised algorithm for generating a single hole is as follows:

Step 1 Set y(0) = a.

Step 2 For each i = 1, 2, . . . , n, let

y(i) = fix(y(i − 1) + r(i))

where r(i) is a random integer chosen from the set {−1, 0, 1} with probabilities P₋₁, P₀ and P₁ percent, respectively (P₋₁ + P₀ + P₁ = 100). And fix is a function defined by

fix(y) = 0 (if y < 0), y (if 0 ≤ y ≤ h), h (if h < y)

which clamps (restricts) its output to the range [0, h].

Step 3 Once we have y(i) for each i = 0, 1, ..., n we fill in each interval (i, i + 1) of the function with the straight line that joins the points (i, y(i)) and (i + 1, y(i + 1)).

Step 4 All of the area under y is filled in with dirt.

Figure F.1: An example with n = 9, h = 6, a = 3. The area of dirt is 42.5. One possible function r: r(1) = 1, r(2) = 1, r(3) = −1, r(4) = 0, r(5) = 1, r(6) = 1, r(7) = 1, r(8) = −1, r(9) = −1.

Since Andrew wants to build many holes, he needs to know how much dirt he will need. Help him by determining the expected area under the terrain for each hole.

입력

The input consists of a single line containing six integers n (1 ≤ n ≤ 100 000), which is the length of the hole, h (0 ≤ h ≤ 100), which is the maximum height of the hole, a (0 ≤ a ≤ h), which is the height at x = 0, P₋₁ (0 ≤ P₋₁ ≤ 100), P₀ (0 ≤ P₀ ≤ 100) and P₁ (0 ≤ P₁ ≤ 100), which are the probability of r being −1, 0 and 1, respectively. In addition, P₋₁ + P₀ + P₁ = 100.

출력

Display the expected area under the terrain. Your answer should have an absolute or relative error of less than 10⁻⁶.

제한

힌트