Day01-刷题

1.句子逆序

• 将一个以英文语句以单词为单位逆序排放,例如:"I am a boy",逆序排放后为"boy a am I",

public String reverse(String sentence) {
    String[] str = sentence.trim().split(" ");
    String result = "";
    int start = 0;
    int end = str.length - 1;
    while (start < end) {
        String t = str[start];
        str[start] = str[end];
        str[end] = t;
        start++;
        end--;
    }
    for (String t : str) {
        result += t;
        //每个单词后面添加一个空格
        result += " ";
    }
    return result.trim();
}

• 扩展思考,把每个单词再进行逆序

public String reverse(String sentence, boolean revertWord) {
    String[] str = sentence.trim().split(" ");
    String result = "";
    String revertStr;
    int start = 0;
    int end = str.length - 1;
    while (start < end) {
        String t = str[start];
        str[start] = str[end];
        str[end] = t;
        start++;
        end--;
    }
    for (String t : str) {
        if (revertWord == true) {
            revertStr = "";
            for (int i = t.length() - 1; i > -1; i--) {
                revertStr = revertStr + t.charAt(i);
            }
            t = revertStr.toString();
        }
        result += t;
        //每个单词后面加一个空格
        result += " ";
    }
    return result.trim();
}