leetcode

0 class Solution {

1 static pair<int, int> count(const string_view &s) {

2 int x = 0, nums = 0, sign = 1;

3 for (int i = 0; i < size(s); i++) {

4 if (s[i] == '+')

5 sign = 1;

6 else if (s[i] == '-')

7 sign = -1;

8 else {

9 int num = s[i] == 'x' ? 1 : 0;

10 while (isdigit(s[i]))

11 num = num * 10 + s[i++] - '0';

12 if (s[i] == 'x')

13 x += sign * num;

14 else

15 nums += sign * num, i--;

16 }

17 }

18

19 return {x, nums};

20 }

21

22 public:

23 string solveEquation(const string &equation) const {

24 const string_view sv(equation);

25 const auto it = sv.find('=');

26

27 const auto [lx, ln] = count({begin(sv), it});

28 const auto [rx, rn] = count(sv.substr(it + 1));

29

30 if (lx == rx) return ln == rn ? "Infinite solutions" : "No solution";

31 return "x=" + to_string((rn - ln) / (lx - rx));

32 }

33 };