You have some coins. The i-th coin has a probability prob[i] of facing heads when tossed. Return the probability that the number of coins facing heads equals target if you toss every coin exactly once. Example 1: Input: prob = [0.4], target = 1 Output: 0.40000 Example 2: Input: prob = [0.5,0.5,0.5,0.5,0.5], target = 0 Output: 0.03125 Constraints: 1 <= prob.length <= 1000 0 <= prob[i] <= 1 0 <= target <= prob.length Answers will be accepted as correct if they are within 10^-5 of the correct answer.