BestApproximationDiv1
SRM 483 · 2010-03-12 · by espr1t
Problem Statement
Elly understands that working with infinite decimal fractions is going to be very difficult, so she first wants to find a good way to approximate floating point numbers with decimal representations that are finite. Your task is to help her in this mission. You will be given a
Given a fraction F = A/B, where 0 <= A < B, its quality of approximation with respect to number is calculated as follows:
- Let S be the decimal fraction (infinite or finite) representation of F.
- If S is infinite or the number of digits after the decimal point in S is greater than 6, only consider the first 6 decimals after the decimal point in S. Truncate the rest of the digits without performing any kind of rounding.
- If the number of digits after the decimal point in S is less than 6, append trailing zeroes to the right side until there are exactly 6 digits after the decimal point.
- The quality of approximation is the number of digits in the longest common prefix of S and number. The longest common prefix of two numbers is the longest string which is a prefix of the decimal representations of both numbers with no extra leading zeroes. For example, "3.14" is the longest common prefix of 3.1428 and 3.1415.
Constraints
- maxDen will be between 1 and 1000, inclusive.
- number will contain exactly 8 characters.
- number will consist of a digit '0', followed by a period ('.'), followed by exactly six digits ('0'-'9').
Statement by TopCoder, Inc. — view the original on the archive.
42 "0.141592" Returns: "1/7 has 3 exact digits"
3 plus the current approximation yields an approximation of Pi.
3 "0.133700" Returns: "0/1 has 1 exact digits"
Not a lot of options here.
1000 "0.123456" Returns: "10/81 has 7 exact digits"
1000 "0.420000" Returns: "21/50 has 7 exact digits"
This one can be represented in more than one way. Be sure to choose the one with the lowest denominator.
100 "0.909999" Returns: "10/11 has 4 exact digits"
Even though 91/100 is a much closer approximation, 10/11 matches up to 3 digits, and 91/100 only to one.
115 "0.141592" Returns: "16/113 has 7 exact digits"
A better approximation for the decimal part of Pi.
42 "0.000000" Returns: "0/1 has 7 exact digits"
Zero
Submissions are judged against all 153 archived test cases, of which 7 are shown here. Case numbers match the judge’s.
Language: C++17 · define a public class BestApproximationDiv1 with a public method string findFraction(int maxDen, string number) · 153 test cases · 2 s / 256 MB per case