Count and Say

Author: sachuverma

DSA Crack Sheet/README.md

@@ -60,7 +60,8 @@
 - [Print all the duplicates in the input string](https://www.geeksforgeeks.org/print-all-the-duplicates-in-the-input-string/ "view topic")
 - [Why strings are immutable in Java?](https://javarevisited.blogspot.com/2010/10/why-string-is-immutable-or-final-in-java.html#:~:text=The%20string%20is%20Immutable%20in,cached%20in%20the%20String%20pool.&text=Since%20Strings%20are%20very%20popular,which%20was%20stored%20in%20HashMap. "view topic")
 - [Check if strings are rotations of each other or not](https://practice.geeksforgeeks.org/problems/check-if-strings-are-rotations-of-each-other-or-not-1587115620/1# "view question") - [Cpp Solution](./solutions/Check%20if%20strings%20are%20rotations%20of%20each%20other%20or%20not.cpp)
-- [Java Program to Check if a string is a valid shuffle of two distinct strings](https://www.programiz.com/java-programming/examples/check-valid-shuffle-of-strings "view topic")
+- [Program to Check if a string is a valid shuffle of two distinct strings](https://www.programiz.com/java-programming/examples/check-valid-shuffle-of-strings "view topic")
+- [Count and Say](https://leetcode.com/problems/count-and-say/ "view question") - [Cpp Solution](./solutions/Count%20and%20Say.cpp)
 - []( "view question") - [Cpp Solution](./solutions/.cpp)
 
 ### Searching & Sorting

DSA Crack Sheet/solutions/Count and Say.cpp

@@ -0,0 +1,64 @@
+/*
+Count and Say
+=============
+
+The count-and-say sequence is a sequence of digit strings defined by the recursive formula:
+
+countAndSay(1) = "1"
+countAndSay(n) is the way you would "say" the digit string from countAndSay(n-1), which is then converted into a different digit string.
+To determine how you "say" a digit string, split it into the minimal number of groups so that each group is a contiguous section all of the same character. Then for each group, say the number of characters, then say the character. To convert the saying into a digit string, replace the counts with a number and concatenate every saying.
+
+For example, the saying and conversion for digit string "3322251":
+
+Given a positive integer n, return the nth term of the count-and-say sequence.
+
+Example 1:
+Input: n = 1
+Output: "1"
+Explanation: This is the base case.
+
+Example 2:
+Input: n = 4
+Output: "1211"
+Explanation:
+countAndSay(1) = "1"
+countAndSay(2) = say "1" = one 1 = "11"
+countAndSay(3) = say "11" = two 1's = "21"
+countAndSay(4) = say "21" = one 2 + one 1 = "12" + "11" = "1211"
+
+Constraints:
+1 <= n <= 30
+*/
+
+class Solution
+{
+public:
+  string countAndSay(int n)
+  {
+    if (n == 1)
+      return "1";
+    auto prev_ans = countAndSay(n - 1);
+
+    string ans = "";
+    int N = prev_ans.size(), count = 1;
+
+    for (int i = 0; i < N; ++i)
+    {
+      if (i == N - 1)
+      {
+        ans += to_string(count);
+        ans += prev_ans[i];
+      }
+      else if (prev_ans[i] == prev_ans[i + 1])
+        count++;
+      else
+      {
+        ans += to_string(count);
+        ans += prev_ans[i];
+        count = 1;
+      }
+    }
+
+    return ans;
+  }
+};