solve problem Student Attendance Record I

Author: P-ppc

README.md

@@ -89,6 +89,7 @@ All solutions will be accepted!
 |696|[Count Binary Substrings](https://leetcode-cn.com/problems/count-binary-substrings/description/)|[java/py/js](./algorithms/CountBinarySubstrings)|Easy|
 |121|[Best Time To Buy And Sell Stock](https://leetcode-cn.com/problems/best-time-to-buy-and-sell-stock/description/)|[java/py/js](./algorithms/BestTimeToBuyAndSellStock)|Easy|
 |599|[Minimum Index Sum Of Two Lists](https://leetcode-cn.com/problems/minimum-index-sum-of-two-lists/description/)|[java/py/js](./algorithms/MinimumIndexSumOfTwoLists)|Easy|
+|551|[Student Attendance Record I](https://leetcode-cn.com/problems/student-attendance-record-i/description/)|[java/py/js](./algorithms/StudentAttendanceRecordI)|Easy|
 
 # Database
 |#|Title|Solution|Difficulty|

algorithms/StudentAttendanceRecordI/README.md

@@ -0,0 +1,2 @@
+# Student Attendance Record I
+This problem is easy to solve

algorithms/StudentAttendanceRecordI/Solution.java

@@ -0,0 +1,26 @@
+class Solution {
+    public boolean checkRecord(String s) {
+        List<Character> aStack = new ArrayList<Character>();
+        List<Character> lStack = new ArrayList<Character>();
+        Character lastCharacter = '0';
+        
+        for (char c : s.toCharArray()) {
+            if (c == 'A') {
+                aStack.add(c);
+            } else if (c == 'L') {
+                if (lastCharacter != c) {
+                    lStack.clear();
+                }
+                lStack.add(c);
+            }
+            
+            if (aStack.size() > 1 || lStack.size() > 2) {
+                return false;
+            }
+            
+            lastCharacter = c;
+        }
+        
+        return true;
+    }
+}

algorithms/StudentAttendanceRecordI/solution.js

@@ -0,0 +1,31 @@
+/**
+ * @param {string} s
+ * @return {boolean}
+ */
+var checkRecord = function(s) {
+    let aStack = [],
+        lStack = [],
+        lastCharacter = null
+    
+    for (let i = 0; i < s.length; i++) {
+        let c = s[i]
+        
+        if (c === 'A') {
+            aStack.push(c)
+        } else if (c === 'L') {
+            if (lastCharacter !== c) {
+                lStack = [c]
+            } else {
+                lStack.push(c)
+            }
+        }
+        
+        if (aStack.length > 1 || lStack.length > 2) {
+            return false
+        }
+        
+        lastCharacter = c
+    }
+    
+    return true
+};

algorithms/StudentAttendanceRecordI/solution.py

@@ -0,0 +1,24 @@
+class Solution(object):
+    def checkRecord(self, s):
+        """
+        :type s: str
+        :rtype: bool
+        """
+        a_stack = []
+        l_stack = []
+        last_character = None
+        
+        for c in s:
+            if c == 'A':
+                a_stack.append(c)
+            elif c == 'L':
+                if last_character != 'L':
+                    l_stack = [c]
+                else:
+                    l_stack.append(c)
+            
+            if len(a_stack) > 1 or len(l_stack) > 2:
+                return False
+            last_character = c
+            
+        return True