Given you an infinite 2-dimensional plane, and find all paths from (0,0) to with some limitation factors: 1.You cannot step to points that under the y-axis. 2.For every step you can perform one of the following operations: move right for 2 steps, e.g. from to move right, then move up, e.g. from to move right, then move down, e.g. from to Now you must find out the numbers of different operation sequences.
Given you an infinite 2-dimensional plane, and find all paths from (0,0) to (2n,0) with some limitation factors: 1.You cannot step to points that under the y-axis. 2.For every step you can perform one of the following operations: (1) move right for 2 steps, e.g. from (x, y) to (x+2, y) (2) move right, then move up, e.g. from (x, y) to (x+1, y+1) (3) move right, then move down, e.g. from (x, y) to (x+1, y-1) Now you must find out the numbers of different operation sequences.
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