Reverse words in a string

Author: zgpeace

code/LeetCode/src/popular/ReverseWordsInAString.java

@@ -0,0 +1,95 @@
+package popular;
+
+public class ReverseWordsInAString {
+
+    public String reverseWords(String s) {
+        s = s.trim();
+        if (s.length() == 0) {
+            return s;
+        }
+        String blankString = " ";
+        String[] wordsArray = s.split(blankString);
+        StringBuilder sb = new StringBuilder();
+
+        for (int i = wordsArray.length - 1; i >= 0; i--) {
+            String word =  wordsArray[i];
+            word = word.trim();
+            if (word.length() > 0) {
+                sb.append(word).append(blankString);
+            }
+        }
+
+        return sb.toString().trim();
+    }
+
+    public String reverseWordsWithLessSpace(String s) {
+        char[] chars = s.toCharArray();
+        int len = chars.length;
+        subReverse(chars, 0, len - 1);
+        subReverseWords(chars, len);
+
+        return subCleanBlankChar(chars, len);
+    }
+
+    public String subCleanBlankChar(char[] chars, int len) {
+        int i = 0, j = 0;
+        char blankChar = ' ';
+        while (j < len) {
+            while (j < len && chars[j] == blankChar) {
+                j++;
+            }
+            while (j < len && chars[j] != blankChar) {
+                chars[i++] = chars[j++];
+            }
+            while (j < len && chars[j] == blankChar) {
+                j++;
+            }
+            if (j < len) {
+                chars[i++] = blankChar;
+            }
+        }
+
+        return new String(chars).substring(0, i);
+    }
+
+    public void subReverseWords(char[] chars, int len) {
+        char blankChar = ' ';
+        int i = 0, j = 0;
+        while (j < len) {
+            while (j < len && chars[j] == blankChar) {
+                j++;
+            }
+            i = j;
+            while (j < len && chars[j] != blankChar) {
+                j++;
+            }
+            subReverse(chars, i, j - 1);
+        }
+    }
+
+    public void subReverse(char[] chars, int startIndex, int endIndex) {
+        while (startIndex < endIndex) {
+            char temp = chars[startIndex];
+            chars[startIndex] = chars[endIndex];
+            chars[endIndex] = temp;
+
+            startIndex++;
+            endIndex--;
+        }
+    }
+
+    public static void main(String[] args) {
+        String input = "the sky is blue";
+        ReverseWordsInAString obj = new ReverseWordsInAString();
+        //System.out.println("Input: \"" + input + "\"\n" + "Output: \"" + obj.reverseWords(input) + "\"") ;
+        System.out.println("Input: \"" + input + "\"\n" + "Output: \"" + obj.reverseWordsWithLessSpace(input) + "\"") ;
+
+        String input1 = "  hello world!  ";
+        //System.out.println("Input: \"" + input1 + "\"\n" + "Output: \"" + obj.reverseWords(input1) + "\"") ;
+        System.out.println("Input: \"" + input1 + "\"\n" + "Output: \"" + obj.reverseWordsWithLessSpace(input1) + "\"") ;
+
+        String input2 = "a good   example";
+        //System.out.println("Input: \"" + input2 + "\"\n" + "Output: \"" + obj.reverseWords(input2) + "\"") ;
+        System.out.println("Input: \"" + input2 + "\"\n" + "Output: \"" + obj.reverseWordsWithLessSpace(input2) + "\"") ;
+    }
+}