P4711 「化学」相对分子质量 代码

#include <bits/stdc++.h>
using namespace std;

double ret=0;

namespace StringUtils {
	pair<string,string> split_half(string s,string::size_type p) {
		string a="",b="";
		for (string::size_type i=0; i<s.size(); i++) {
			if (i<p) {
				a+=s[i];
			}
			if (i>p) {
				b+=s[i];
			}
		}
		return make_pair(a,b);
	}
}

map<string,double> che;

void initram() {
	che[""]=0;
	che["H"]=1;
	che["C"]=12;
	che["N"]=14;
	che["O"]=16;
	che["F"]=19;
	che["Na"]=23;
	che["Mg"]=24;
	che["Al"]=27;
	che["Si"]=28;
	che["P"]=31;
	che["S"]=32;
	che["Cl"]=35.5;
	che["K"]=39;
	che["Ca"]=40;
	che["Mn"]=55;
	che["Fe"]=56;
	che["Cu"]=64;
	che["Zn"]=65;
	che["Ag"]=108;
	che["I"]=127;
	che["Ba"]=137;
	che["Hf"]=178.5;
	che["Pt"]=195;
	che["Au"]=197;
	che["Hg"]=201;
}

double normal_produce(string s,string::size_type l=0,string::size_type r=0,bool primary=true) {
	double res = 0;
	string element_buffer = "";
	double element_count=1;
	string::size_type i=l;
	bool least_group=false;
	double group_size=0;
	if (r==0) {
		r=s.length()-1;
	}
	for (; i<=r; i++) {
		if (isupper(s[i])) {
			res += (element_count * che[element_buffer]);
			res += (group_size * least_group);
			element_buffer = "";
			element_buffer += s[i];
			element_count = 1;
			least_group = 0;
		} else if (islower(s[i])) {
			element_buffer += s[i];
		} else if (s[i] == '_' && !least_group) {
			element_count = 0;
			int j;
			for (j=i+1;; j++) {
				if (s[j]=='}') {
					break;
				} else if (isdigit(s[j])) {
					element_count = element_count * 10 + (s[j]-'0');
				}
			}
			i=j-1;
		} else if (s[i]=='_' && least_group) {
			double tv=0;
			int j;
			for (j=i+1;; j++) {
				if (s[j]=='}') {
					break;
				} else if (isdigit(s[j])) {
					tv = tv * 10 + (s[j]-'0');
				}
			}
			res += tv*group_size;
			group_size = 0;
			least_group = 0;
			i=j;
		} else if (s[i]=='(') {
			res += (che[element_buffer] * element_count);
			res += (group_size * least_group);
			element_buffer = "";
			element_count = 1;
			int j;
			int rv=0;
			for (j=i;;j++) {
				if (s[j]=='(') {
					rv++;
				}
				if (s[j]==')') {
					rv--;
				}
				if (rv<=0) {
					break;
				}
			}
			group_size=normal_produce(s,i+1,j-1,false);
			least_group = 1;
			i=j;
		}
	}
	res += (che[element_buffer] * element_count);
	res += (group_size * least_group);
	if (primary) {
		ret += res;
		return 0;
	} else {
		return res;
	}
}

void hydrate_produce(string s) {
	int water_count=0;
	int cursor=0;
	for (string::size_type i=0; i<s.length(); i++) {
		if (isdigit(s[i])) {
			cursor++;
			water_count=water_count*10+(s[i]-'0');
		} else {
			break;
		}
	}
	if (cursor == 0) {
		water_count = 1;
	}
	ret += (water_count * 18);
}

int main() {
	initram();
	int spliter=-1145141;
	string s;
	cin>>s;
	for (string::size_type i=0; i<s.length(); i++) {
		if (s[i]=='~') {
			spliter=i;
			break;
		}
	}
	if (spliter<0) {
		normal_produce(s);
	} else {
		pair<string,string> splited = StringUtils::split_half(s,spliter);
		normal_produce(splited.first);
		hydrate_produce(splited.second);
	}
	if(ret==(int)(ret)){
		cout<<(int)ret;
	}
	else{
		printf("%.1f",ret);
	}
	return 0;
}