Add a solution to StudentAttendanceRecordI

Author: soapyigu

String/StudentAttendanceRecordI.swift

@@ -0,0 +1,36 @@
+/**
+ * Question Link: https://leetcode.com/problems/student-attendance-record-i/
+ * Primary idea: Iterate the string and check late & absent counts to check the eligibility.
+ *
+ * Time Complexity: O(n), Space Complexity: O(1)
+ *
+ */
+
+class StudentAttendanceRecordI {
+    func checkRecord(_ s: String) -> Bool {
+        var ACount = 0, LCount = 0
+        let sChars = Array(s)
+        
+        for i in 0..<s.count {
+            if sChars[i] == "A" {
+                ACount += 1
+                
+                if ACount >= 2 {
+                    return false
+                }
+            } else if sChars[i] == "L" {
+                if i > 0 && sChars[i - 1] == "L" {
+                    LCount += 1
+                    
+                    if LCount >= 3 {
+                        return false
+                    }
+                } else {
+                    LCount = 1
+                }
+            }
+        }
+        
+        return true
+    }
+}