557. Reverse Words in a String III

Given a string, you need to reverse the order of characters in each word within a sentence while still preserving whitespace and initial word order.

Example 1: Input: "Let's take LeetCode contest" Output: "s'teL ekat edoCteeL tsetnoc"

class Solution {
    //置反单个单词
    public static String reverseString(String s) {
        int len=s.length();
        char []b=new char[len];
        for (char a : s.toCharArray()) {
            b[len-1] = a;
            len--;
        }
        String end = new String(b);
        return end;
    }
    //置反整条字符串
    public String reverseWords(String s) {
        char a[] = s.toCharArray();
        //确定单个单词个数
        int count=1;
        for (int i = 0; i < a.length; i++) 
            if(a[i]==' ')
                count++;
        int j=0;
        //设置数组b，用来存放置反后的单词
        String b[] = new String[count];
        for (int i = 0; i < count; i++) {
            b[i] = new String();
        }

        for (int i = 0; i < b.length; i++) {
            while(j < a.length) {
                if(a[j]==' ') {
                    b[i] = reverseString(b[i])+" ";
                    j++;
                    break;
                }
                b[i]+=a[j];
                j++;
            }
        }
        //处理最后一个单词
        b[count-1] = reverseString(b[count-1]);
        String string = new String();
        for (int i = 0; i < b.length; i++) 
            string+=b[i];

        return string;
    }
}