Minimum time to reach the cell should be less than or equal to given time.

The answer is true if <code>t</code> is greater or equal than the Chebyshev distance from <code>(sx, sy)</code> to <code>(fx, fy)</code>. However, there is one more edge case to be considered.

The answer is false If <code>sx == fx</code> and <code>sy == fy</code>