思路

和上一道题一样，只不过这道题需要倒序进去倒序输出就ok了

#include<bits/stdc++.h>
using namespace std;
char a[10000];
char b[10000];//存一下转成后缀输出的，然后再倒序输出
int main()
{
	stack <char> s;
	cin>>a;
	int num=0;
	for(int i=strlen(a)-1;i>=0;i--){
		if(a[i]<='9'&&a[i]>='0'){
			b[num]=a[i];
			num++;
		}
		else if(a[i]=='+'||a[i]=='-'){
			if(s.empty()){
				s.push(a[i]);
			}
			else{
				while(!s.empty()&&s.top()!=')'){
					b[num]=s.top();
					s.pop();
					num++;
				}
				s.push(a[i]);
			}
		}
		else if(a[i]=='*'||a[i]=='/'){
			if(!s.empty()){
				while(!s.empty()&&s.top()=='*'||s.top()=='/'){
					b[num]=s.top();
					num++;
					s.pop();
				}
				s.push(a[i]); 
			}
			else{
				s.push(a[i]);
			}
			
		}
		else if(a[i]==')'){
			s.push(a[i]);
		}
		else if(a[i]=='('){
			while(!s.empty()&&s.top()!=')'){
				b[num]=s.top();
				num++;
				s.pop();
			}
			s.pop();
		}
	}
	while(!s.empty()){
		b[num]=s.top();
		num++;
		s.pop();
	}
	for(int i=num-1;i>=0;i--){
		cout<<b[i];
	}
	return 0;
}

使用两个栈的做法：

#include<bits/stdc++.h>
using namespace std;
int main()
{
	char i[1005];
	scanf("%s",i);
	int k=strlen(i);
	stack<char> pp;
	stack<char> dd;
 	for(int c=k-1;c>=0;c--){
		int l=i[c]-'0';
		if(l>=0&&l<=9) pp.push(i[c]);
		else{
			if(dd.empty()) dd.push(i[c]);
			else if(i[c]==')') dd.push(i[c]);
			else if(i[c]=='*'||i[c]=='/'){
				dd.push(i[c]);
			}else if(i[c]=='-'||i[c]=='+'){
				while(dd.top()!='-'&&dd.top()!='+'&&dd.top()!=')'){
					pp.push(dd.top());
					dd.pop();
					if(dd.empty()) break;
					if(dd.top()==')') break;
				}
				dd.push(i[c]);
			}else if(i[c]=='('){
				while(dd.top()!=')'){
					pp.push(dd.top());
					dd.pop();
				}
				dd.pop();
			}
		}
	}
	while(!dd.empty()){
		pp.push(dd.top());
		dd.pop();
	}
	while(!pp.empty()){
		cout<<pp.top();
		pp.pop();
	}
	return 0;
}

和上道题差不多，不过改一下判断条件

#include<iostream>
#include<cstring>
#include<stack>
using namespace std;
const int N=1007;
int f=99999;
char a[N];
stack<char>s1;
stack<char>s2;
int main(){
	gets(a);
	int n=strlen(a);
		for(int i=n-1;i>=0;i--){
		int k=9;
		if(a[i]=='*')k=1;
		if(a[i]=='/')k=1;
		if(a[i]=='+')k=0;
		if(a[i]=='-')k=0;
		if(a[i]=='(')k=3;
		if(a[i]==')')k=3;
		if(a[i]>='0'&&a[i]<='9')
			s1.push(a[i]);
		else if(k==1||k==0){
			if(s2.empty())
				s2.push(a[i]);
			else {
				if(s2.top()==')'||k<=f){
					s2.push(a[i]);
				}
				else {
					while(1){
						if(s2.empty())
							break;
						if(s2.top()==')')
							break;
						s1.push(s2.top());
						s2.pop();
					}
					s2.push(a[i]);
				}
			}
		}
		else if(k==3){
			if(a[i]=='('){
				while(s2.top()!=')'){
					s1.push((s2.top()));
					s2.pop();
				}
				s2.pop();
			}
			else s2.push(a[i]);
		}
		f=k;
	}
	while(!s2.empty()){
		s1.push((s2.top()));
		s2.pop();
	}
	while(!s1.empty()){
		cout<<s1.top();
		s1.pop();
	}
	return 0;
}

#include<stdio.h>
#include<string.h>
#include<stack>
#include<queue>
using namespace std;
int main()
{
  char arr2[1000];
  char arr[1000];
  scanf("%s",arr);
  stack<char>room;
  int j = 0;
  for(int i = strlen(arr) - 1; i >= 0; i--)
  {
  	if(arr[i] >= 48 && arr[i] <= 57)
  	{
  		arr2[j] = arr[i];
  		j ++;
	  }
	else if(arr[i] == ')' || arr[i] == '(')
	{
		if(arr[i] == ')')room.push(arr[i]);
		else
		{
			while(room.top() != ')')
	  	    {
	  		if(room.size() == 0)break;
	  		arr2[j] = room.top();
	  		j ++;
			room.pop();
		    }
		room.pop();
		}	
	}
	else
	{
		if(room.size() == 0)
		{
			room.push(arr[i]);
		}
		else
		{
			if(arr[i] == '*' || arr[i] == '/')room.push(arr[i]);
			else if(arr[i] == '+' )
			{
				if(room.top() == '+' || room.top() == '-'||room.top() == ')')room.push(arr[i]);
				else
				{
						while(room.size() != '+' || room.top() != '-')
						{
						   arr2[j] = room.top();
						   j ++;
						    room.pop();
							if(room.size() == 0)break;	
						}
						 room.push(arr[i]);
				}
			}
			else
			{
				if(room.top() == '-' || room.top() == '(')room.push(arr[i]);\
				else
				{
					while(room.top() != '-'&&room.top() != ')')
					{
						arr2[j] = room.top();
						j ++;
						room.pop();
				  		if(room.size() == 0)break;
					}
					room.push(arr[i]);
				}
			}
		}
	}
	}
	 while(room.size() != 0)
	 {
	 	arr2[j] = room.top();
	 	j++;
	 	room.pop();
	 	if(room.size() == 0)break;
	 }
	 while(j--)
	 {
	 	printf("%c",arr2[j]);
	 }
  return 0;
}