New Problem Solution - "Minimum Changes To Make Alternating Binary String"

Author: haoel

README.md

@@ -9,6 +9,7 @@ LeetCode
 
 | # | Title | Solution | Difficulty |
 |---| ----- | -------- | ---------- |
+|1758|[Minimum Changes To Make Alternating Binary String](https://leetcode.com/problems/minimum-changes-to-make-alternating-binary-string/) | [C++](./algorithms/cpp/minimumChangesToMakeAlternatingBinaryString/MinimumChangesToMakeAlternatingBinaryString.cpp)|Easy|
 |1754|[Largest Merge Of Two Strings](https://leetcode.com/problems/largest-merge-of-two-strings/) | [C++](./algorithms/cpp/largestMergeOfTwoStrings/LargestMergeOfTwoStrings.cpp)|Medium|
 |1753|[Maximum Score From Removing Stones](https://leetcode.com/problems/maximum-score-from-removing-stones/) | [C++](./algorithms/cpp/maximumScoreFromRemovingStones/MaximumScoreFromRemovingStones.cpp)|Medium|
 |1752|[Check if Array Is Sorted and Rotated](https://leetcode.com/problems/check-if-array-is-sorted-and-rotated/) | [C++](./algorithms/cpp/checkIfArrayIsSortedAndRotated/CheckIfArrayIsSortedAndRotated.cpp)|Easy|

algorithms/cpp/minimumChangesToMakeAlternatingBinaryString/MinimumChangesToMakeAlternatingBinaryString.cpp

@@ -0,0 +1,53 @@
+// Source : https://leetcode.com/problems/minimum-changes-to-make-alternating-binary-string/
+// Author : Hao Chen
+// Date   : 2021-02-14
+
+/***************************************************************************************************** 
+ *
+ * You are given a string s consisting only of the characters '0' and '1'. In one operation, you can 
+ * change any '0' to '1' or vice versa.
+ * 
+ * The string is called alternating if no two adjacent characters are equal. For example, the string 
+ * "010" is alternating, while the string "0100" is not.
+ * 
+ * Return the minimum number of operations needed to make s alternating.
+ * 
+ * Example 1:
+ * 
+ * Input: s = "0100"
+ * Output: 1
+ * Explanation: If you change the last character to '1', s will be "0101", which is alternating.
+ * 
+ * Example 2:
+ * 
+ * Input: s = "10"
+ * Output: 0
+ * Explanation: s is already alternating.
+ * 
+ * Example 3:
+ * 
+ * Input: s = "1111"
+ * Output: 2
+ * Explanation: You need two operations to reach "0101" or "1010".
+ * 
+ * Constraints:
+ * 
+ * 	1 <= s.length <= 104
+ * 	s[i] is either '0' or '1'.
+ ******************************************************************************************************/
+
+class Solution {
+public:
+    int minOperations(string s) {
+        int start_with_zero = 0;
+        int start_with_one = 0;
+        for (int i=0; i<s.size(); i++){
+            if (i % 2 == 0) {
+                s[i] == '1' ? start_with_zero++ : start_with_one++;
+            }else{
+                s[i] == '0' ? start_with_zero++ : start_with_one++;
+            }
+        }
+        return std::min(start_with_zero, start_with_one);
+    }
+};