Backspace String Compare.cpp

/*  
    So basically whenever we encounter a backspcae character, the character preceeding it wil get deleted.

    As backspace will delete the characters after which they will come, so idea is to start traversing from the back and maintain the no. of characters to skip/delete 
    TC: O(N+M) ; Space: O(1)
*/

class Solution {
public:
    bool backspaceCompare(string s, string t) 
    {
        int i=s.length()-1, j=t.length()-1;
        int sSkip = 0, tSkip = 0;
        
        while(i>=0 || j>=0)
        {
            while(i>=0)
            {
                if(s[i]=='#')
                {
                    sSkip++;
                    i--;
                }
                else if(sSkip>0)    // skip all the characters that will be deleted by the backspace
                {
                    sSkip--;
                    i--;
                }
                else        // this means we're at a char, which will not get deleted and we're supposed to compare this char
                    break;
            }
            while(j>=0)
            {
                if(t[j]=='#')
                {
                    tSkip++;
                    j--;
                }
                else if(tSkip>0)    // skip all the characters that will be deleted by the backspace
                {
                    tSkip--;
                    j--;
                }
                else
                    break;
            }
            if(i>=0 && j>=0 && s[i]!=t[j])  // if after skipping all characters we reach at a posistion, and there characters aren't equal then return false, becz they can't be skipped anymore
                return false;        
            if(i>=0 != j>=0)    // if one of the string get emptied before other
                return false;
    
            i--;
            j--;
        }
        return true;
    }
};