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2022.04.01(LC_1047_删除字符串中的所有相邻重复项)

正义的杰克船长 2022-04-01 阅读 83
java

方法一:Deque作为栈

class Solution {
    public String removeDuplicates(String s) {
        Deque<Character> stack = new LinkedList<>();
        for (char ch : s.toCharArray()) {
            if (stack.isEmpty() || ch != stack.peek()) {
                stack.push(ch);
            } else {
                stack.pop();
            }
        }
        StringBuilder sb = new StringBuilder();
        while (!stack.isEmpty()) {
            sb.append(stack.pop());
        }
        return sb.reverse().toString();
    }
}

方法二:StringBuilder作为栈

class Solution {
    public String removeDuplicates(String s) {
        StringBuilder sb = new StringBuilder();
        int top = -1;
        for (char ch : s.toCharArray()) {
            if (top >= 0 && ch == sb.charAt(top)) {
                sb.deleteCharAt(top);
                top--;
            } else {
                sb.append(ch);
                top++;
            }
        }
        return sb.toString();
    }
}

方法三:数组作为栈

class Solution {
    public String removeDuplicates(String s) {
        char[] str = s.toCharArray();
        int top = -1;
        for (char ch : s.toCharArray()) {
            if (top == -1 || ch != str[top]) {
                str[++top] = ch;
            } else {
                top--;
            }
        }
        //public static String valueOf​(char[] data, int offset, int count)
        //offset参数是第一个字符的索引,count参数指定长度
        return String.valueOf(str, 0, top + 1);
    }
}
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