C++14 解法, 执行用时: 2ms, 内存消耗: 404KB, 提交时间: 2020-09-03

#include <iostream>
#include <map>
#include <string>
#include <vector>
#include <stdlib.h>
using namespace std;
typedef map<string, int> mst;
string hxs;
int posi = 0;
int len;
mst ele;

int getdigit()
{
	int num = 0;
	while ('0' <= hxs[posi] && hxs[posi] <= '9')
	{
		num = num * 10 + hxs[posi] - '0';
		if (posi<len)
			posi++;
	}
	return num;
}

void mapAdd(mst& map1, mst& map2)
{
	for (auto m : map2)
	{
		map1[m.first] += m.second;
	}
}

void solve(mst &ans)
{
	mst mp;
	string pr;
	while (posi < len)
	{
		if (hxs[posi] == ')')
		{
			if (pr != "")
			{
				mp[pr]++;
			}
			posi++;
			int mlp = getdigit();
			mst::iterator p = mp.begin();
			while(p!=mp.end())
			{
				p->second = p->second * mlp;
				p++;
			}
			mapAdd(ans, mp);
			return;
		}
		if (hxs[posi] == '(')
		{
			if (pr != "")
			{
				mp[pr]++;
				pr = "";
			}
			posi++;
			solve(mp);
		}
		if ('A' <= hxs[posi] && hxs[posi] <= 'Z')
		{
			if (pr!="")
			{
				mp[pr]++;
				pr = "";
				pr.push_back(hxs[posi]);
			}
			else
			{
				pr.push_back(hxs[posi]);
			}
			posi++;
		}
		if ('a' <= hxs[posi] && hxs[posi] <= 'z')
		{
			pr.push_back(hxs[posi]);
			posi++;
		}
		if ('0' <= hxs[posi] && hxs[posi] <= '9')
		{
			int mlp = getdigit();
			mp[pr] = mp[pr] + mlp;
			pr = "";
		}
		if (hxs[posi] == '\0')
		{
			if (pr != "")
			{
				mp[pr]++;
			}
		}
	}
	mapAdd(ele, mp);
	return;
}



int main()
{
	cin >> hxs;
	len = hxs.length();
	mst m;
	solve(m);
	for (auto rslt : ele)
	{
		if (rslt.second > 1)
			cout << rslt.first << rslt.second;
		else cout << rslt.first;
	}
	cout << endl;
	return 0;
}

C++ 解法, 执行用时: 2ms, 内存消耗: 488KB, 提交时间: 2019-08-21

#include <iostream>
#include <vector>
#include <string>
#include <deque>
#include <map>
using namespace std;
int main()
{
	int mtipule=1;
	deque<int> muti1;
	int kuohao=0,geshu=0;
	vector<string> elem;
	vector<int> elem_geshu;
	string s,temp_int="",temp_elem="";
    cin>>s;
	for(int i=s.size()-1;i>=0;i--)
	{
	   if(s[i]>='0'&&s[i]<='9')
		   temp_int=s[i]+temp_int;
	   else
	   {
		   if(temp_int!="")
		   {
			   muti1.push_front(atoi(temp_int.c_str()));
			   mtipule=mtipule*atoi(temp_int.c_str());
			   geshu++;
			   temp_int="";
		   }
		   if(s[i]>='a'&&s[i]<='z')
		   {
			   temp_elem=s[i]+temp_elem;
		   }
		    if(s[i]>='A'&&s[i]<='Z')
		   {
			   elem.push_back(s[i]+temp_elem);
                elem_geshu.push_back(mtipule);
			   //cout<<s[i]+temp_elem<<" "<<mtipule<<endl;
			   if(geshu>kuohao)
			   {
				    if(mtipule!=1)
				   {
				   mtipule=mtipule/muti1.front();
				   muti1.pop_front();
				   }
				   geshu--;
			   }
			   temp_elem="";
		   }
		   else 
		   {
			   if(s[i]==')')
				   kuohao++;
			   if(s[i]=='(')
			   {
				   if(mtipule!=1)
				   {
				   mtipule=mtipule/muti1.front();
				   muti1.pop_front();
				   }
				   geshu--;
				   kuohao--;
			   }
		   }
	   }

	}
	map<string,int> m1;
	for(int i=0;i<elem.size();i++)
	{
		m1[elem[i]]=m1[elem[i]]+elem_geshu[i];
	}
	map<string,int>::iterator iter;  
  
    for(iter = m1.begin(); iter != m1.end(); iter++)
    {
        if(iter->second==1)
            cout<<iter->first;
        else
       cout<<iter->first<<iter->second;  
    }
	cout<<endl;
	return 0;
}