How hard is LeetCode 1230. Toss Strange Coins?

LeetCode 1230. Toss Strange Coins is rated Medium on LeetCode.

What is the time complexity of LeetCode 1230. Toss Strange Coins?

The Python solution on this page runs in O(n \times target).

What is the space complexity of LeetCode 1230. Toss Strange Coins?

The Python solution on this page uses O(target) auxiliary space.

What topics does LeetCode 1230. Toss Strange Coins cover?

LeetCode 1230. Toss Strange Coins is tagged Array, Math, Dynamic Programming and Probability and Statistics on LeetCode.

Is LeetCode 1230. Toss Strange Coins a premium problem?

Yes. LeetCode 1230. Toss Strange Coins is a LeetCode Premium problem, so the full statement and test cases require a paid LeetCode subscription.

Toss Strange Coins — LeetCode 1230 Python Solution

MediumLeetCode PremiumArrayMathDynamic ProgrammingProbability and Statistics

Problem: #1230
Pattern: Dynamic Programming
Reading time: 2 min
Source: leetcode.com

The problem

You have some coins. The i-th coin has a probability prob[i] of facing heads when tossed.

Example

Input: prob = [0.4], target = 1
Output: 0.40000

Python solution

Python

class Solution:
    def probabilityOfHeads(self, prob: List[float], target: int) -> float:
        n = len(prob)
        f = [[0] * (target + 1) for _ in range(n + 1)]
        f[0][0] = 1
        for i, p in enumerate(prob, 1):
            for j in range(min(i, target) + 1):
                f[i][j] = (1 - p) * f[i - 1][j]
                if j:
                    f[i][j] += p * f[i - 1][j - 1]
        return f[n][target]

Complexity

Measure	Complexity
Time	O(n \times target)
Space	O(target) auxiliary

Pattern: Dynamic Programming

Define a state, write the transition, and stop recomputing the same subproblem. LeetCode 1230. Toss Strange Coins is filed here on both counts: the reference solution below belongs to the algorithm family this hub collects, and LeetCode tags it Dynamic Programming.

The dynamic programming guide has the Python template for the pattern and the 481 LeetCode problems that use it.

Frequently asked questions

How hard is LeetCode 1230. Toss Strange Coins?: LeetCode 1230. Toss Strange Coins is rated Medium on LeetCode.
What is the time complexity of LeetCode 1230. Toss Strange Coins?: The Python solution on this page runs in O(n \times target).
What is the space complexity of LeetCode 1230. Toss Strange Coins?: The Python solution on this page uses O(target) auxiliary space.
What topics does LeetCode 1230. Toss Strange Coins cover?: LeetCode 1230. Toss Strange Coins is tagged Array, Math, Dynamic Programming and Probability and Statistics on LeetCode.
Is LeetCode 1230. Toss Strange Coins a premium problem?: Yes. LeetCode 1230. Toss Strange Coins is a LeetCode Premium problem, so the full statement and test cases require a paid LeetCode subscription.