Create rearrange-words-in-a-sentence.cpp

Author: kamyu104

C++/rearrange-words-in-a-sentence.cpp

@@ -0,0 +1,55 @@
+// Time:  O(nlogn)
+// Space: O(n)
+
+class Solution {
+public:
+    string arrangeWords(string text) {
+        text.front() = tolower(text.front());
+        stringstream ss(text);
+        string word;
+        map<int, string> lookup;
+        while (ss >> word) {
+            lookup[word.size()] += word + " ";
+        }
+        string result;
+        for (const auto& [_, word]: lookup) {
+            result += word;
+        }
+        result.pop_back();
+        result.front() = toupper(result.front());
+        return result;
+    }
+};
+
+// Time:  O(nlogn)
+// Space: O(n)
+class Solution2 {
+public:
+    string arrangeWords(string text) {
+        text.front() = tolower(text.front());
+        auto words = split(text, ' ');
+        stable_sort(begin(words), end(words),
+                    [](const string &s1, const string &s2) {
+                        return s1.size() < s2.size();
+                    });
+        string result;
+        for (const auto& word : words) {
+            result += word + " ";
+        }
+        result.pop_back();
+        result.front() = toupper(result.front());
+        return result;
+    }
+
+private:
+    vector<string> split(const string& s, const char delim) {
+        vector<string> result;
+        auto end = string::npos;
+        do {
+            const auto& start = end + 1;
+            end = s.find(delim, start);
+            result.emplace_back(s.substr(start, end - start));
+        } while (end != string::npos); 
+        return result;
+    }
+};