[LeetCode] Reverse Words in a String

原題:https://oj.leetcode.com/problems/reverse-words-in-a-string/

題解：該題通過Java來解非常簡單，通過split函數按空格分隔即可，但是本題有很多陷阱；比如字符串收尾有空格，或本身就是一個空格；這時就需要去判斷分隔後的元素的長度，代碼如下：

public class Solution {
public String reverseWords(String s) {
        if(s == null)
            return s;
        String[] sa = s.split(" ");
        StringBuilder sb = new StringBuilder();
        boolean first = true;
        for(int i = sa.length-1; i >= 0; i--){
            if(sa[i].length() != 0){
                if(first){
                    sb.append(sa[i]);
                    first = false;
                }
                else{
                    sb.append(" ").append(sa[i]);
                }
            }
        }
        return sb.toString();
    }
}