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Java-based LeetCode algorithm problem solutions, regularly updated
837\. New 21 Game
Medium
Alice plays the following game, loosely based on the card game **"21"**.
Alice starts with `0` points and draws numbers while she has less than `k` points. During each draw, she gains an integer number of points randomly from the range `[1, maxPts]`, where `maxPts` is an integer. Each draw is independent and the outcomes have equal probabilities.
Alice stops drawing numbers when she gets `k` **or more points**.
Return the probability that Alice has `n` or fewer points.
Answers within 10-5
of the actual answer are considered accepted.
**Example 1:**
**Input:** n = 10, k = 1, maxPts = 10
**Output:** 1.00000
**Explanation:** Alice gets a single card, then stops.
**Example 2:**
**Input:** n = 6, k = 1, maxPts = 10
**Output:** 0.60000
**Explanation:** Alice gets a single card, then stops. In 6 out of 10 possibilities, she is at or below 6 points.
**Example 3:**
**Input:** n = 21, k = 17, maxPts = 10
**Output:** 0.73278
**Constraints:**
* 0 <= k <= n <= 104
* 1 <= maxPts <= 104