| # | Title | Solutions | Time | Space | Difficulty | Tag | Notes

|-----|----------------|---------------|---------------|---------------|-------------|--------------|-----

|557|[Reverse Words in a String III](https://leetcode.com/problems/reverse-words-in-a-string-iii/)|[Solution](../../master/leetcode-algorithms/src/main/java/com/stevesun/solutions/ReverseWordsinaStringIII.java) | O(n) |O(n) | Easy | String

|548|[Split Array with Equal Sum](https://leetcode.com/problems/split-array-with-equal-sum/)|[Solution](../../master/leetcode-algorithms/src/main/java/com/stevesun/solutions/SplitArraywithEqualSum.java) | O(n^2) |O(1) | Medium | Array

|547|[Friend Circles](https://leetcode.com/problems/friend-circles/)|[Solution](../../master/leetcode-algorithms/src/main/java/com/stevesun/solutions/FriendCircles.java) | O(n^2) |O(n) | Medium | Union Find

|545|[Boundary of Binary Tree](https://leetcode.com/problems/boundary-of-binary-tree/)|[Solution](../../master/leetcode-algorithms/src/main/java/com/stevesun/solutions/BoundaryofBinaryTree.java) | O(n) |O(n) | Medium | Recursion

packagecom.stevesun.solutions;

publicclassReverseWordsinaStringIII {

publicStringreverseWords(Strings) {

StringBuilderstringBuilder =newStringBuilder();

StringBuildersbUtils =newStringBuilder();

for (Stringword :s.split(" ")) {

sbUtils.setLength(0);

sbUtils.append(word);

stringBuilder.append(sbUtils.reverse().toString());

stringBuilder.append(" ");

}

stringBuilder.setLength(stringBuilder.length()-1);

returnstringBuilder.toString();

}

}