package com.leetcode;
import java.util.LinkedList;
import java.util.List;
public class BackspaceStringCompare {
//https://leetcode.com/problems/backspace-string-compare/
class Solution {
/**
* "ab##"
* "c#d#"
*
* or
*
* "bxj##tw"
* "bxo#j##tw"
* Special case
**/
//Follow up: O(1) Space
public boolean backspaceCompare(String S, String T) {
int ns = S.length();
int nt = T.length();
int i = ns - 1;
int j = nt - 1;
while (true) {//cannot check i>=0 and j>=0 as both shoud finish
int back = 0;
while (i >= 0 && (back > 0 || S.charAt(i) == '#')) {
if (S.charAt(i) == '#') {
back++;
} else {
back--;
}
i--;
}
back = 0;
while (j >= 0 && (back > 0 || T.charAt(j) == '#')) {
if (T.charAt(j) == '#') {
back++;
} else {
back--;
}
j--;
}
if (i >= 0 && j >= 0 && S.charAt(i) == T.charAt(j)) {
i--;
j--;
} else {
break;
}
}
//System.out.print(i + "" + j);
return i == -1 && j == -1;//covered all index
}
}
}
/**
//With Memory and use of List
String sT = trasnform(S);
String tT = trasnform(T);
System.out.print(sT+" " + tT);
return sT.equals(tT);
public String trasnform(String s){
int n = s.length();
List ch = new LinkedList();
for(char c : s.toCharArray()){
if(c != '#'){
ch.add(c);
}else{
if(ch.size() > 0)
ch.remove(ch.size()-1);
}
}
return String.valueOf(ch);
}
}
**/