844. 比较含退格的字符串

844. 比较含退格的字符串

class Solution {
    public boolean backspaceCompare(String S, String T) {
        int len1 = S.length();
        int len2 = T.length();
        Deque<Character> stack1 = new LinkedList<>();
        Deque<Character> stack2 = new LinkedList<>();
        for (int i = 0; i < len1; i++) {
            Character c = S.charAt(i);
            if (!stack1.isEmpty() && c == '#') {
                stack1.pollLast();
            } else if (stack1.isEmpty() && c== '#') {
                continue;
            } else {
                stack1.offerLast(c);
            }
        }
        for (int i = 0; i < len2; i++) {
            Character c = T.charAt(i);
            if (!stack2.isEmpty() && c == '#') {
                stack2.pollLast();
            } else if (stack2.isEmpty() && c == '#') {
                continue;
            } else {
                stack2.offerLast(c);
            }
        }
        if (stack1.size() != stack2.size()) {
            return false;
        }
        while (!stack1.isEmpty() && !stack2.isEmpty()) {
            Character c1 = stack1.pollFirst();
            Character c2 = stack2.pollFirst();
            if (c1 != c2) {
                return false;
            }
        }
        return true;
    }
}

class Solution {
    public boolean backspaceCompare(String S, String T) {
        int len1 = S.length() - 1;
        int len2 = T.length() - 1;
        int skip1 = 0;
        int skip2 = 0;
        while (len1 >= 0 || len2 >= 0) {
            while (len1 >= 0) {
                if (S.charAt(len1) == '#') {
                    ++skip1;
                    --len1;
                } else if (skip1 > 0) {
                    --skip1;
                    --len1;
                } else {
                    break;
                }
            }
            while (len2 >= 0) {
                if (T.charAt(len2) == '#') {
                    ++skip2;
                    --len2;
                } else if (skip2 > 0) {
                    --skip2;
                    --len2;
                } else {
                    break;
                }
            }
            if (len1 >= 0 && len2 >= 0) {
                if (S.charAt(len1) != T.charAt(len2)) {
                    return false;
                }
            } else {
                if (len1 >= 0 || len2 >= 0) {
                    return false;
                }
            }
            --len1;
            --len2;
        }
        return true;
    }
}