单词倒排c++

#include<iostream>
#include<string>
using namespace std;
int main()
{
    string input;
    string output;
    int count =0;
    int pos = 0;
    getline(cin, input);
    if(input.size() <= 1) {cout << input;}
    for(int i = 0; i < input.size(); ++i)
    {
        if(input[i] >= 'a' && input[i] <= 'z' || input[i] >='A' && input[i] <='Z')
        {
            output.insert(pos,1,input[i]);
            pos++;
        }
        else  if(!(input[i] >= 'a' && input[i] <= 'z' || input[i] >='A' && input[i] <='Z'))
        {
            if(!(input[i-1] >= 'a' && input[i-1] <= 'z' || input[i-1] >='A' && input[i-1] <='Z'))
            {
                continue;
            }
            else
            {
                output.insert(0,1,' ');
                pos = 0;
            }
        }
    }
    for(auto c : output)
    {
        cout << c;
    }
    return 0;
}