d891320478's blog

Round #129 div2 Problem #c
By d891320478, 12 years ago, In English

Don't use (int)log10(n)+1 to count the length of n.

It may cause error because of accuracy.

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12 years ago, # |
  Vote: I like it +3 Vote: I do not like it

Instead, try this:

int digits(int x){ //works for x>0, for x<0 simply put x=-x, and for x==0 return 1
   int result=0;
   while (x>0){
      result++;
      x/=10;
   }
   return result;
}

It's just a few lines of code. I know speed is crucial here, but this can be typed in 15 seconds. Using floating point arithmetic for things that can be done with integer arithmetic is not recommended.

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    12 years ago, # ^ |
    ← Rev. 2   Vote: I like it 0 Vote: I do not like it

    Here's an even faster way :)

    1. Integer.valueOf(x).toString().length();

    2. (""+x).toString().length();

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      12 years ago, # ^ |
        Vote: I like it +1 Vote: I do not like it

      even faster and in C:

      len=sprintf(buf,"%d",x);

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        12 years ago, # ^ |
          Vote: I like it 0 Vote: I do not like it

        Quite elegant, but, the code i posted works in every base and takes a lot less time because it doesn't rely on string operations. Whatever suits people's needs.

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        12 years ago, # ^ |
        ← Rev. 2   Vote: I like it 0 Vote: I do not like it

        Yours is shorter, but it takes longer to type.

        1. Integer.toString(x).length();

        2. Integer.toString(x,17).length(); // Different base

        Since it's a string operation I use it when I know it won't effect too much on the speed.

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