add a solution for 186

fishercoder1534 · fishercoder1534 · commit 60b74f424798 · 2021-07-08T08:31:25.000-07:00
diff --git a/src/main/java/com/fishercoder/solutions/_186.java b/src/main/java/com/fishercoder/solutions/_186.java
@@ -1,43 +1,55 @@
 package com.fishercoder.solutions;
 
-/**
- * 186. Reverse Words in a String II
-
- Given an input string, reverse the string word by word. A word is defined as a sequence of non-space characters.
-
- The input string does not contain leading or trailing spaces and the words are always separated by a single space.
-
- For example,
- Given s = "the sky is blue",
- return "blue is sky the".
-
- Could you do it in-place without allocating extra space?
- */
 public class _186 {
-  public static class Solution1 {
-    public void reverseWords(char[] s) {
-      // Three steps to reverse
-      // 1, reverse the whole sentence
-      reverse(s, 0, s.length - 1);
-      // 2, reverse each word
-      int start = 0;
-      for (int i = 0; i < s.length; i++) {
-        if (s[i] == ' ') {
-          reverse(s, start, i - 1);
-          start = i + 1;
+    public static class Solution1 {
+        public void reverseWords(char[] s) {
+            // Three steps to reverse
+            // 1, reverse the whole sentence
+            reverse(s, 0, s.length - 1);
+            // 2, reverse each word
+            int start = 0;
+            for (int i = 0; i < s.length; i++) {
+                if (s[i] == ' ') {
+                    reverse(s, start, i - 1);
+                    start = i + 1;
+                }
+            }
+            // 3, reverse the last word, if there is only one word this will solve the corner case
+            reverse(s, start, s.length - 1);
+        }
+
+        private void reverse(char[] s, int start, int end) {
+            while (start < end) {
+                char temp = s[start];
+                s[start++] = s[end];
+                s[end--] = temp;
+            }
         }
-      }
-      // 3, reverse the last word, if there is only one word this will solve the corner case
-      reverse(s, start, s.length - 1);
     }
 
-    private void reverse(char[] s, int start, int end) {
-      while (start < end) {
-        char temp = s[start];
-        s[start++] = s[end];
-        s[end--] = temp;
-      }
+    public static class Solution2 {
+        public void reverseWords(char[] s) {
+            reverse(s, 0, s.length);
+            for (int i = 0; i < s.length; i++) {
+                int start = i;
+                while (i < s.length && s[i] != ' ') {
+                    i++;
+                }
+                reverse(s, start, i);
+            }
+        }
+
+        private void reverse(char[] chars, int start, int end) {
+            int left = start;
+            int right = end - 1;
+            while (left < right) {
+                char tmp = chars[left];
+                chars[left] = chars[right];
+                chars[right] = tmp;
+                left++;
+                right--;
+            }
+        }
     }
-  }
 
 }
