sinasadi's blog

By sinasadi, 10 years ago, In English

please say me , how solve this problem with this tag ---> " math " ?! are there other problems like this in math (not in programming) that i practis on them to solve this one ? B. Jumping Jack

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10 years ago, # |
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After n jumps, if you jump always to the right, you'll be at point p = 1 + 2 + 3 + 4 + ... + n. If, instead of jumping right, you jumped left in the kth jump, you would be at point p - 2k. Moreover, by carefully choosing which jumps to go left and which to go right, after n jumps, you can be at any point between n * (n + 1) / 2 and  - (n * (n + 1) / 2) with the same parity as n * (n + 1) / 2. So, what you must do is simulate the jumping process, always jumping to the right, and if at some point, you've reached a point that has the same parity as x and is at or beyond x, you'll have your answer.