Fraction to Recurring Decimal(STRING-TYPE CONVERTION)
QUESTION
Given two integers representing the numerator and denominator of a fraction, return the fraction in string format.
If the fractional part is repeating, enclose the repeating part in parentheses.
For example,
Given numerator = 1, denominator = 2, return "0.5".
Given numerator = 2, denominator = 1, return "2".
Given numerator = 2, denominator = 3, return "0.(6)".
1ST TRY
class Solution { public: string fractionToDecimal(int numerator, int denominator) { char* ch = new char(); string ret; string fractionStr = ""; int remain; vector<bool> flag(10, false); //integer part *ch = numerator/denominator +'0'; ret = ch; //fraction part while(1) { remain = numerator%denominator; if(remain == 0) return ret; else if(flag[remain]) return ret + ".(" + fractionStr + ")"; else { flag[remain] = true; *ch = numerator/denominator +'0'; fractionStr += ch; } } } };
Result: Runtime Error
Last executed input: -50, 8
2ND TRY
考虑了负数情况
class Solution { public: string fractionToDecimal(int numerator, int denominator) { string intStr = ""; string fractionStr = ""; string tmpStr = ""; int remain; vector<bool> flag(10, false); // int 转 string stringstream ss; //negative or not if(numerator > 0 && denominator < 0) { intStr = "-"; denominator = ~(denominator-1); } else if(numerator < 0 && denominator > 0) { intStr = "-"; numerator = ~(numerator-1); } else if(numerator < 0 && denominator < 0) { numerator = ~(numerator-1); denominator = ~(denominator-1); } //integer part ss << numerator/denominator; ss >> tmpStr; intStr += tmpStr; remain = numerator%denominator; if(remain == 0) return intStr; //fraction part while(1) { if(remain == 0) return intStr + "." + fractionStr; else if(flag[remain]) return intStr + ".(" + fractionStr + ")"; else { flag[remain] = true; numerator = remain * 10; remain = numerator%denominator; ss.clear(); ss << numerator/denominator; ss >> tmpStr; fractionStr += tmpStr; } } } };
Result: Runtime Error
Last executed input: -2147483648, -10
3RD TRY
考虑溢出的情况
class Solution { public: string fractionToDecimal(int numerator, int denominator) { long long int num = (long long int) numerator; long long int den = (long long int) denominator; string intStr = ""; string fractionStr = ""; string tmpStr = ""; int remain; set<int> flag; // int 转 string stringstream ss; //negative or not if(num > 0 && denominator < 0) { intStr = "-"; den = ~(den-1); } else if(num < 0 && den > 0) { intStr = "-"; num = ~(num-1); } else if(num < 0 && den < 0) { num = ~(num-1); den = ~(den-1); } //integer part ss << num/den; ss >> tmpStr; intStr += tmpStr; remain = num%den; if(remain == 0) return intStr; //fraction part while(1) { if(remain == 0) return intStr + "." + fractionStr; else if(flag.find(remain)!=flag.end()) return intStr + ".(" + fractionStr + ")"; else { flag.insert(remain); num = remain * 10; remain = num%den; ss.clear(); ss << num/den; ss >> tmpStr; fractionStr += tmpStr; } } } };
Result: Wrong
Input: 1, 6
Output: "0.(16)"
Expected: "0.1(6)"
4TH TRY
循环的位置得准确，所以用map代替set
class Solution { public: string fractionToDecimal(int numerator, int denominator) { long long int num = (long long int) numerator; long long int den = (long long int) denominator; string ret = ""; string tmpStr = ""; int remain; map<int,int> flag; // int 转 string stringstream ss; //negative or not if(num > 0 && denominator < 0) { ret = "-"; den = ~(den-1); } else if(num < 0 && den > 0) { ret = "-"; num = ~(num-1); } else if(num < 0 && den < 0) { num = ~(num-1); den = ~(den-1); } //integer part ss << num/den; ss >> tmpStr; ret += tmpStr; remain = num%den; if(remain == 0) return ret; //fraction part ret += "."; while(1) { if(remain == 0) return ret; else if(flag.find(remain)!=flag.end()) { ret.insert(flag[remain], 1, '('); return ret + ")"; } else { flag[remain] = ret.length(); num = remain * 10; remain = num%den; ss.clear(); ss << num/den; ss >> tmpStr; ret += tmpStr; } } } };
Result: Wrong
Input: -1, -2147483648
Output: "0.000000000000000000000000000000-1"
Expected: "0.0000000004656612873077392578125"
5TH TRY
remain也要申请为long long int, 否则在num = remain * 10;会溢出
class Solution { public: string fractionToDecimal(int numerator, int denominator) { long long int num = (long long int) numerator; long long int den = (long long int) denominator; string ret = ""; string tmpStr = ""; long long int remain; map<int,int> flag; // int 转 string stringstream ss; //negative or not if(num > 0 && denominator < 0) { ret = "-"; den = ~(den-1); } else if(num < 0 && den > 0) { ret = "-"; num = ~(num-1); } else if(num < 0 && den < 0) { num = ~(num-1); den = ~(den-1); } //integer part ss << num/den; ss >> tmpStr; ret += tmpStr; remain = num%den; if(remain == 0) return ret; //fraction part ret += "."; while(1) { if(remain == 0) return ret; else if(flag.find(remain)!=flag.end()) { ret.insert(flag[remain], 1, '('); return ret + ")"; } else { flag[remain] = ret.length(); num = remain * 10; remain = num%den; ss.clear(); ss << num/den; ss >> tmpStr; ret += tmpStr; } } } };
Result: Accepted