i2p.cpp

来自「设计一个算法」· C++ 代码 · 共 87 行

#include<iostream.h>
#include<iomanip.h>
#include<fstream.h>
#include<string.h>
#include<ctype.h>
#define MAX 100000
#define MMIN (200000000)
int main()
{
	long tmp,StringLen,p1,t1,i,len;
	char st[MAX];
	ifstream input("input.txt");
	input >> st+1;
	ofstream output("output.txt");
	st[0]='(';
	StringLen=strlen(st);
    st[StringLen]=')';    //加括号
	StringLen++;
	st[StringLen]='\0';

	len=strlen(st);
	long *NumStack=new long [len];
	char *SymbolStack=new char [len];

	p1=t1=0;
	for(i=0;i<StringLen;i++)
	{
		if (isspace(st[i])) continue;
		else if (isdigit(st[i]))
		{
			tmp=0;
			while(isdigit(st[i]))
			{
				tmp=tmp*10+st[i]-'0';
				i++;
			}
			i--;
			NumStack[++p1]=tmp;
		}
		else
		{
				switch (st[i])         //check
				{
					case '+':       
					case '-':        //+,-
						while(SymbolStack[t1]!='(')
						{
							NumStack[++p1]=SymbolStack[t1]-MMIN;
							SymbolStack[t1--]=0;
						}
						SymbolStack[++t1]=st[i];
						break;
					case '*':
					case '/': 
					case '%':  //*,/,%
						while(SymbolStack[t1]=='*' || SymbolStack[t1]=='/' || SymbolStack[t1]=='%')
						{
							NumStack[++p1]=SymbolStack[t1]-MMIN;
							SymbolStack[t1--]=0;
						}
						SymbolStack[++t1]=st[i];
						break;
					case '(':       //'('
						SymbolStack[++t1]=st[i];
						break;
					case ')':        //')'
						while(SymbolStack[t1]!='(')
						{
							NumStack[++p1]=SymbolStack[t1]-MMIN;
							SymbolStack[t1--]=0;
						}
						SymbolStack[t1--]=0;       //pop
						break;
				}
		}
	} 
	for(i=1;i<=p1;i++)
		if (NumStack[i]<0)
			output<<char(NumStack[i]-MMIN)<<" ";     
		else 
			output<<NumStack[i]<<" ";
 		output<<endl;
	delete[] NumStack;
	delete[] SymbolStack;
	return 0;
}