Added solution1 for 30-days-of-leetcode

Author: avidLearnerInProgress

30-days-of-code-may/01.firstBadVersion.cpp

@@ -0,0 +1,22 @@
+// The API isBadVersion is defined for you.
+// bool isBadVersion(int version);
+
+class Solution {
+public:
+    int firstBadVersion(int n) {
+       
+        int start = 1, end = n, mid;
+        
+        while(start < end){
+            
+            mid = start + (end - start)/2;
+            if(isBadVersion(mid)){
+                end = mid;
+            }
+            else{
+                start = mid + 1;
+            }
+        }
+        return start;
+    }
+};