rprudhvi590's blog

By rprudhvi590, history, 7 weeks ago, In English,
  • Given an integer n, find and return the n'th magic number
  • A magic number is defined as a number which can be expressed as a power of 7 or sum of unique powers of 7
  • First four magic numbers are  7 ,  49 ,  56 (7 + 49),  343,etc . constraint 1<=n<=pow(10,18) i have implemented the solution as follows:

https://ideone.com/Q8OM0b but it gives me wrong answer,the only difference is that when calculating the value of add we need to apply mod;and the solution is as follows:

https://ideone.com/k1KhFA

how will we know where to apply a mod operator..pls help.

 
 
 
 
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7 weeks ago, # |
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its better to apply after every operation.

say, a + b * c, do it like (a + (b*c) % mod ) % mod

also take care of case of int overflow, either use long long or while(x < 0) x = x + mod.

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7 weeks ago, # |
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