leetcode

Solution to some Leetcode problems written in C++

git clone git://git.dimitrijedobrota.com/leetcode.git

0065.cpp (1428B)

0 class Solution { 1 using it_t = string::const_iterator; 2 3 static bool validSign(it_t &pos, const it_t &end) { 4 if (*pos == '-' || *pos == '+') { 5 pos++; 6 if (find(pos, end, '-') != end || find(pos, end, '+') != end) { 7 return false; 8 } 9 } 10 11 return pos != end; 12 } 13 14 static bool validDigit(const it_t &pos, const it_t &end) { 15 return all_of(pos, end, [](char c) { return isdigit(c); }); 16 } 17 18 static bool isDecimal(const string &s) { 19 auto pos = begin(s); 20 21 if (!validSign(pos, end(s))) return false; 22 if (string(pos, end(s)) == ".") return false; 23 24 auto dot = find(pos, end(s), '.'); 25 return validDigit(pos, dot) && validDigit(dot + 1, end(s)); 26 } 27 28 static bool isInteger(const string &s) { 29 auto pos = begin(s); 30 if (!validSign(pos, end(s))) return false; 31 return validDigit(pos, end(s)); 32 } 33 34 public: 35 bool isNumber(const string &s) const { 36 auto e = s.find('e'), E = s.find('E'); 37 38 if (E != string::npos) swap(e, E); 39 if (e != string::npos) { 40 const string first = s.substr(0, e); 41 const string second = s.substr(e + 1); 42 return !first.empty() && !second.empty() && isInteger(second) && 43 (isDecimal(first) || isInteger(first)); 44 } 45 46 return isDecimal(s) || isInteger(s); 47 } 48 };