中缀表达式转后缀表达式.cpp

#include<limits>
#include<queue>
#include<vector>
#include<list>
#include<map>
#include<set>
#include<deque>
#include<stack>
#include<bitset>
#include<algorithm>
#include<functional>
#include<numeric>
#include<utility>
#include<sstream>
#include<iostream>
#include<iomanip>
#include<cstdio>
#include<cmath>
#include<cstdlib>
#include<cstring>
#include<ctime>
#define LL __int64
#define eps 1e-8
#define pi acos(-1)
using namespace std;
string s="";
string ans="";
stack<char>st;
map<char,int>mp;
int go(char c){
	if (mp.find(c)==mp.end()) return 0;
	if (st.empty() || c=='('){
		st.push(c);
		return 1;
	}
	if (c==')'){
		while (1){
			if (st.empty()) return 0;
			char k=st.top();
			st.pop();
			if (k=='(') return 1;
			ans+=k;
		}
	}
	char k=st.top();
	if (mp[c]>mp[k]){
		st.push(c);
		return 1;
	}else{
		while (mp[c]<=mp[k] && !st.empty() && k!='('){
			st.pop();
			ans+=k;
			if (st.empty()) break;
			k=st.top();
		}
		st.push(c);
		return 1;
	}
}
int main(){
	mp['+']=0;mp['-']=0;mp['*']=1;mp['/']=1;mp['%']=1;mp[')']=0;mp['(']=0;
	printf("请输入正确的中缀表达式:\n");
	cin>>s;
	int l=s.length();
	for (int i=0;i<l;i++){
		if (s[i]>'0' && s[i]<'9') ans+=s[i];
		else if (!go(s[i])){
				printf("错误的中缀表达式！\n");
				return 0; 
			}
	}
	while (!st.empty()){
		ans+=st.top();
		st.pop();
	}
	cout<<ans<<endl;
	return 0;
}