Prob: 186 Reverse words in a sentence

Author: mandliya

README.md

@@ -6,7 +6,7 @@
 
 | Current Status|     Stats     |
 | :------------: | :----------: |
-| Total Problems | 185 |
+| Total Problems | 186 |
 
 </center>
 
@@ -269,3 +269,7 @@ pattern = "abba", str = "dog dog dog dog" should return false.| [word_pattern.cp
 price of a stock on ith day. If you are permitted to only complete 
 one transaction per day (i.e buy one and sell one stock), design
 an algorithm to find the maximum profit.| [best_time_to_buy_sell.cpp](leet_code_problems/best_time_to_buy_sell.cpp)|
+| Given a sentence, reverse the order of characters in each word within a sentence while still preserving whitespace and initial word order.|
+ Example: 
+ Input:  She loves    chocolate 
+ Output: ehs sevol    etalocohc|[reverse_words.cpp](leet_code_problems/reverse_words.cpp)|

leet_code_problems/reverse_words.cpp

@@ -0,0 +1,42 @@
+/*
+ * Given a string, you need to reverse the order of characters in each word within a sentence
+ *  while still preserving whitespace and initial word order.
+ * 
+ * Example:
+ * Input:  She loves    chocolate 
+ * Output: ehs sevol    etalocohc
+ * 
+ * Approach:
+ * Use two indices to figure out non-whitespace characters, and reverse
+ * the portion.
+ */
+
+#include <iostream>
+#include <string>
+
+
+std::string reverse_words(std::string& sentence)
+{
+    for(int i = 0; i < sentence.length(); ++i) {
+        if (sentence[i] != ' ') {
+            int j = i;
+            // let j find the end of non-whitespace portion
+            while (j < sentence.length() &&
+                sentence[j] != ' ') {
+                j++;
+            }
+            std::reverse(sentence.begin() + i, sentence.begin() + j);
+            // reset i to next word.
+            i = j - 1;
+        } 
+    }
+    return sentence;
+}
+
+int main()
+{
+    std::string sentence{"She loves    chocolate"};
+    std::cout << "Input:  " << sentence << std::endl;
+    std::cout << "Output: " << reverse_words(sentence) << std::endl;
+    return 0; 
+}