Molar mass UVA - 1586

答案如下

#include<bits/stdc++.h>
using namespace std;
const double c=12.01,h=1.008,o=16.00,n=14.01;
int main()
{
	int x;
	cin>>x;
    for(int i=0;i<x;i++)
	{
		
		char s[100];
		cin>>s;
		double an=0;
		for(int i=0;i<strlen(s);i++)
		{
			if(s[i]=='C')
			{
				if(s[i+1]>='0'&&s[i+1]<='9'&&s[i+2]>='0'&&s[i+2]<='9')
					an+=((s[i+1]*10-'0'*10+s[i+2]-'0')*c);
				else if(s[i+1]>='0'&&s[i+1]<='9')
				    an+=((s[i+1]-'0')*c);
				else an+=c;
			}
			if(s[i]=='H')
			{
				if(s[i+1]>='0'&&s[i+1]<='9'&&s[i+2]>='0'&&s[i+2]<='9')
					an+=((s[i+1]*10-'0'*10+s[i+2]-'0')*h);
				else if(s[i+1]>='0'&&s[i+1]<='9')
				    an+=((s[i+1]-'0')*h);
				else an+=h;
			}
			if(s[i]=='O')
			{
				if(s[i+1]>='0'&&s[i+1]<='9'&&s[i+2]>='0'&&s[i+2]<='9')
					an+=((s[i+1]*10-'0'*10+s[i+2]-'0')*o);
				else if(s[i+1]>='0'&&s[i+1]<='9')
				    an+=((s[i+1]-'0')*o);
				else an+=o;
			}
			if(s[i]=='N')
			{
				if(s[i+1]>='0'&&s[i+1]<='9'&&s[i+2]>='0'&&s[i+2]<='9')
					an+=((s[i+1]*10-'0'*10+s[i+2]-'0')*n);
				else if(s[i+1]>='0'&&s[i+1]<='9')
				    an+=((s[i+1]-'0')*n);
				else an+=n;
			}
		}
		printf("%.3f\n",an);
	}
	return 0;
}