SHOW:
|
|
- or go back to the newest paste.
1 | #include<iostream> | |
2 | #include<map> | |
3 | #include<string> | |
4 | #include<sstream> | |
5 | #include<regex> | |
6 | ||
7 | std::string derivative(std::string polynomial) { | |
8 | std::regex m("[+]?([-]?[0-9]*)[\\*]?(x?)[\\^]?([0-9]*)"); | |
9 | std::smatch sm; | |
10 | std::map<int, int> pow_k; | |
11 | ||
12 | while(regex_search(polynomial, sm, m) && polynomial.size() > 0) | |
13 | { | |
14 | int k = atoi(std::string(sm[1]).c_str()); | |
15 | int pow = atoi(std::string(sm[3]).c_str()); | |
16 | if (std::string(sm[2]) == "x") | |
17 | { | |
18 | if (pow == 0) pow = 1; | |
19 | if (k == 0) k = 1; | |
20 | if (std::string(sm[1]) == "-") k = -1; | |
21 | } | |
22 | ||
23 | pow_k[pow] += k; | |
24 | polynomial = sm.suffix(); | |
25 | } | |
26 | ||
27 | std::ostringstream result; | |
28 | auto begin = pow_k.rbegin(); | |
29 | auto end = pow_k.rend(); | |
30 | auto gets = [](int pow, int k){ | |
31 | std::ostringstream member; | |
32 | member << k * pow; | |
33 | if (pow > 1) member << "*x"; | |
34 | if (pow > 2) member << '^' << pow-1; | |
35 | return member.str(); | |
36 | }; | |
37 | if (begin != end) | |
38 | { | |
39 | result << gets( begin->first, begin->second ); | |
40 | ++begin; | |
41 | } | |
42 | for(; begin != end; ++begin) | |
43 | { | |
44 | if ( begin->first == 0 ) continue; | |
45 | if ( begin->second > 0 ) result << '+'; | |
46 | result << gets( begin->first, begin->second ); | |
47 | } | |
48 | return result.str(); | |
49 | } | |
50 | ||
51 | int main() | |
52 | { | |
53 | #ifdef AZHUKOV | |
54 | freopen("input.txt", "r", stdin); | |
55 | #endif | |
56 | std::string in; | |
57 | std::cin >> in; | |
58 | std::cout << derivative(in) << std::endl; | |
59 | return 0; | |
60 | } |