Equal Rational Numbers Problem

Description

LeetCode Problem 972.

Given two strings s and t, each of which represents a non-negative rational number, return true if and only if they represent the same number. The strings may use parentheses to denote the repeating part of the rational number.

A rational number can be represented using up to three parts: , , and a . The number will be represented in one of the following three ways:

• For example, 12, 0, and 123.
• <.>
• For example, 0.5, 1., 2.12, and 123.0001.
• <.><(><)>
• For example, 0.1(6), 1.(9), 123.00(1212).

The repeating portion of a decimal expansion is conventionally denoted within a pair of round brackets. For example:

• 1/6 = 0.16666666… = 0.1(6) = 0.1666(6) = 0.166(66).

Example 1:

``````1
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Input: s = "0.(52)", t = "0.5(25)"
Output: true
Explanation: Because "0.(52)" represents 0.52525252..., and "0.5(25)" represents 0.52525252525..... , the strings represent the same number.
``````

Example 2:

``````1
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Input: s = "0.1666(6)", t = "0.166(66)"
Output: true
``````

Example 3:

``````1
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Input: s = "0.9(9)", t = "1."
Output: true
Explanation: "0.9(9)" represents 0.999999999... repeated forever, which equals 1.  [<a href="https://en.wikipedia.org/wiki/0.999..." target="_blank">See this link for an explanation.</a>]
"1." represents the number 1, which is formed correctly: (IntegerPart) = "1" and (NonRepeatingPart) = "".
``````

Constraints:

• Each part consists only of digits.
• The does not have leading zeros (except for the zero itself).
• 1 <= .length <= 4
• 0 <= .length <= 4
• 1 <= .length <= 4

Sample C++ Code

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class Solution {
public:
// Transform string to double
bool isRationalEqual(string S, string T) {
return f(S) == f(T);
}
double f(string S) {
auto i = S.find("(");
if (i != string::npos) {
string base = S.substr(0, i);
string rep = S.substr(i + 1, S.length() - i - 2);
for (int j = 0; j < 20; ++j)
base += rep;
return stod(base);
}
return stod(S);
}
};
``````