151.reverse-words-in-a-string.java

/*
 * @lc app=leetcode id=151 lang=java
 *
 * [151] Reverse Words in a String
 */

// @lc code=start
class Solution {
    public String reverseWords(String s) {
        s = s.trim();
        char[] c = s.toCharArray();
        char[] reverseWords = reverseWord(c);
        String str =  new String(reverseWords);
        String[] parts = str.split("\\s+");
        String ress = "";
        int flag = 0;
        for (String part : parts) {
            char[] ca = part.toCharArray();
            char[] res = reverseWord(ca);
            String strr =  new String(res);
            if (flag == 0) {
                ress += strr;
                flag = 1;
            } else {
                ress += " " + strr;
            }
        }
        return ress;
    }

    private char[] reverseWord(char[] c) {
        int i = 0;
        int j = c.length - 1;
        while (i < j) {
            char temp = c[i];
            c[i] = c[j];
            c[j] = temp;
            i++;
            j--;
        }
        return c;
    }
}
// @lc code=end

/* 
class Solution {
    public String reverseWords(String s) {
        StringBuilder sb = removeSpace(s);
        reverseString(sb, 0, sb.length() - 1);
        reverseEachWord(sb);
        return sb.toString();
    }
    private StringBuilder removeSpace(String s) {
        int start = 0;
        int end = s.length() - 1;
        while (s.charAt(start) == ' ') start++;
        while (s.charAt(end) == ' ') end--;
        StringBuilder sb = new StringBuilder();
        while (start <= end) {
            char c = s.charAt(start);
            if (c != ' ' || sb.charAt(sb.length() - 1) != ' ') {
                sb.append(c);
            }
            start++;
        }
        return sb;
    }
    public void reverseString(StringBuilder sb, int start, int end) {
        while (start < end) {
            char temp = sb.charAt(start);
            sb.setCharAt(start, sb.charAt(end));
            sb.setCharAt(end, temp);
            start++;
            end--;
        }
    }
    private void reverseEachWord(StringBuilder sb) {
        int start = 0;
        int end = 1;
        int n = sb.length();
        while (start < n) {
            while (end < n && sb.charAt(end) != ' ') {
                end++;
            }
            reverseString(sb, start, end - 1);
            start = end + 1;
            end = start + 1;
        }
    }
} */