OA - Flappy Bird Jump Strategy

Full Interview Question: "OA - Flappy Bird Jump Strategy" at Coinbase

Problem Overview

In a simplified Flappy Bird simulator, implement a function shouldJump(...) that decides on every frame whether the bird should jump and apply an upward impulse. An evaluator runs your function to simulate the game and assess your strategy.

Problem Statement

Given a simplified Flappy Bird game, you need to implement a function shouldJump(...) that determines whether the bird should jump or not on each frame. The function will receive the current state of the game and should return a boolean indicating whether to jump. The state includes the bird's position, the pipes' positions, and the velocity of the bird. The goal is to maximize the score by avoiding collisions with the pipes.

Constraints

1. The bird's position is given as a tuple (x, y), where x is the horizontal position and y is the vertical position.
2. The pipes' positions are given as a list of tuples (x, gap_start, gap_end), where x is the horizontal position of the pipe, and gap_start and gap_end are the vertical positions of the top and bottom of the gap, respectively.
3. The bird's velocity is given as a tuple (dx, dy), where dx is the horizontal velocity and dy is the vertical velocity.
4. The bird can only jump once per frame.

Examples

Example 1: Input: bird_position=(100, 0), pipes=[(50, 100, 200), (150, 50, 150)], bird_velocity=(0, 0) Output: True In this example, the bird is at position (100, 0) and there are two pipes. The first pipe has a gap between 100 and 200, and the second pipe has a gap between 50 and 150. The bird's velocity is (0, 0). Since the bird is below the first pipe's gap and above the second pipe's gap, it should jump to avoid collision.

Example 2: Input: bird_position=(200, 50), pipes=[(100, 100, 200), (250, 50, 150)], bird_velocity=(0, 0) Output: False In this example, the bird is at position (200, 50) and there are two pipes. The first pipe has a gap between 100 and 200, and the second pipe has a gap between 50 and 150. The bird's velocity is (0, 0). Since the bird is already within the second pipe's gap, it should not jump.

Hints

1. Consider the bird's current position, velocity, and the positions of the pipes to determine if a jump is necessary.
2. Analyze the bird's trajectory to predict if it will collide with any pipe.
3. Implement a strategy to maximize the score by avoiding collisions and minimizing the number of jumps.

Solution

`python def shouldJump(bird_position, pipes, bird_velocity): x, y = bird_position dx, dy = bird_velocity

# Check if the bird is within a pipe's gap
for pipe in pipes:
    pipe_x, gap_start, gap_end = pipe
    if pipe_x < x and y < gap_start or y > gap_end:
        return True

# Check if the bird is falling below a pipe's gap
for pipe in pipes:
    pipe_x, gap_start, gap_end = pipe
    if pipe_x < x and y > gap_end and dy > 0:
        return True

# Check if the bird is rising above a pipe's gap
for pipe in pipes:
    pipe_x, gap_start, gap_end = pipe
    if pipe_x < x and y < gap_start and dy < 0:
        return True

return False

`

This solution checks if the bird is within a pipe's gap, falling below a pipe's gap, or rising above a pipe's gap. If any of these conditions are met, the function returns True, indicating that the bird should jump. Otherwise, it returns False, indicating that the bird should not jump.

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Search Results:

• GitHub: Flappy Bird AI - A repository with an AI implementation for Flappy Bird.
• LeetCode: Flappy Bird Game - A similar problem on LeetCode.
• PracHub: Flappy Bird Simulator - A practice problem on Prachub.

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