class Solution {

public:

    string reverseOnlyLetters(string s) {

        //用栈或者双指针即可

        //two-pointer

        int n=s.size();

        int left=0,right=n-1;

        while(left<right)

        {

            //这样写是错误的：~((s[left]>='A'&&s[left]<='Z')||(s[left]>='a'&&s[left]<='z') 按位取反以及逻辑取非不一样

            //写法和快排思路相似

            while(left<right && !((s[left]>='A'&&s[left]<='Z')||(s[left]>='a'&&s[left]<='z')))

            {

                //cout<<~((s[left]>='A'&&s[left]<='Z')||(s[left]>='a'&&s[left]<='z'))<<endl;

                left++;

            }

             cout<<left<<endl;

            while(left<right && !((s[right]>='A'&&s[right]<='Z')||(s[right]>='a'&&s[right]<='z')))

            {

                right--;

            }

            //cout<<left<<"-"<<right<<endl;

            if(left<right)

            {

                //cout<<left<<"-"<<right<<endl;

                char tmp=s[left];

                s[left]=s[right];

                s[right]=tmp;

                left++;

                right--;

            }

        }

        return s;

    }

};