题解 | #单词消消乐#

利用Stack的先进先出特性，将字符串转换为的字符挨个装入时，与最顶端的字符比较，若相同，弹出字符，该字符不装入，否则，装入字符。最后转为字符串，返回。

public String WordsMerge (String[] Words) {
        // write code here
        if (Words == null) {
            return "";
        }
        Stack<Character> stack =  new Stack<>();
        for (int i = 0; i < Words.length; i++) {
            int size = Words[i].length();
            for (int j = 0; j < size; j++) {
                if (stack.isEmpty())
                    stack.push(Words[i].charAt(j));
                else {
                    char x = stack.peek();
                    if (x != Words[i].charAt(j)) {
                        stack.push(Words[i].charAt(j));
                    } else {
                        stack.pop();
                    }
                }
            }
        }
        String str = "";
        while (!stack.isEmpty()) {
            str = stack.pop() + "" + str;
        }
        return str;
    }