New Problem Solution -"1816. Truncate Sentence"

README.md

@@ -9,6 +9,7 @@ LeetCode
 
 | # | Title | Solution | Difficulty |
 |---| ----- | -------- | ---------- |
+|1816|[Truncate Sentence](https://leetcode.com/problems/truncate-sentence/) | [C++](./algorithms/cpp/truncateSentence/TruncateSentence.cpp)|Easy|
 |1808|[Maximize Number of Nice Divisors](https://leetcode.com/problems/maximize-number-of-nice-divisors/) | [C++](./algorithms/cpp/maximizeNumberOfNiceDivisors/MaximizeNumberOfNiceDivisors.cpp)|Hard|
 |1807|[Evaluate the Bracket Pairs of a String](https://leetcode.com/problems/evaluate-the-bracket-pairs-of-a-string/) | [C++](./algorithms/cpp/evaluateTheBracketPairsOfAString/EvaluateTheBracketPairsOfAString.cpp)|Medium|
 |1806|[Minimum Number of Operations to Reinitialize a Permutation](https://leetcode.com/problems/minimum-number-of-operations-to-reinitialize-a-permutation/) | [C++](./algorithms/cpp/minimumNumberOfOperationsToReinitializeAPermutation/MinimumNumberOfOperationsToReinitializeAPermutation.cpp)|Medium|

algorithms/cpp/truncateSentence/TruncateSentence.cpp

@@ -0,0 +1,67 @@
+// Source : https://leetcode.com/problems/truncate-sentence/
+// Author : Hao Chen
+// Date   : 2021-04-05
+
+/***************************************************************************************************** 
+ *
+ * A sentence is a list of words that are separated by a single space with no leading or trailing 
+ * spaces. Each of the words consists of only uppercase and lowercase English letters (no punctuation).
+ * 
+ * 	For example, "Hello World", "HELLO", and "hello world hello world" are all sentences.
+ * 
+ * You are given a sentence s​​​​​​ and an integer k​​​​​​. You want to truncate s​​​​​​ such that it 
+ * contains only the first k​​​​​​ words. Return s​​​​​​ after truncating it.
+ * 
+ * Example 1:
+ * 
+ * Input: s = "Hello how are you Contestant", k = 4
+ * Output: "Hello how are you"
+ * Explanation:
+ * The words in s are ["Hello", "how" "are", "you", "Contestant"].
+ * The first 4 words are ["Hello", "how", "are", "you"].
+ * Hence, you should return "Hello how are you".
+ * 
+ * Example 2:
+ * 
+ * Input: s = "What is the solution to this problem", k = 4
+ * Output: "What is the solution"
+ * Explanation:
+ * The words in s are ["What", "is" "the", "solution", "to", "this", "problem"].
+ * The first 4 words are ["What", "is", "the", "solution"].
+ * Hence, you should return "What is the solution".
+ * 
+ * Example 3:
+ * 
+ * Input: s = "chopper is not a tanuki", k = 5
+ * Output: "chopper is not a tanuki"
+ * 
+ * Constraints:
+ * 
+ * 	1 <= s.length <= 500
+ * 	k is in the range [1, the number of words in s].
+ * 	s consist of only lowercase and uppercase English letters and spaces.
+ * 	The words in s are separated by a single space.
+ * 	There are no leading or trailing spaces.
+ ******************************************************************************************************/
+
+class Solution {
+private:
+    bool isAlpha(const char& ch) {
+        return (ch >='a' && ch <='z') || (ch >= 'A' && ch <='Z') ;
+    }
+public:
+    string truncateSentence(string s, int k) {
+        s += ' '; //for edge case
+        bool wordStart = false;
+        int i=0;
+        for (; i< s.size(); i++) {
+            if (!wordStart && isAlpha(s[i])) {
+                wordStart = true;
+            }else if (wordStart && !isAlpha(s[i])) {
+                if (--k <= 0) break;
+                wordStart = false;
+            }
+        }
+        return s.substr(0, i);
+    }
+};