g0801_0900.s0837_new_21_game

Class Solution

java.lang.Object

g0801_0900.s0837_new_21_game.Solution

public class Solution
extends Object

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

Constructor Summary

Constructors

Constructor and Description
Solution()

Method Summary

Modifier and Type	Method and Description
double	new21Game(int n, int k, int w)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Solution

public Solution()

Method Detail

new21Game

public double new21Game(int n,
                        int k,
                        int w)