solves #3168: Minimum Number of Chairs in a Waiting Room in java

Author: anishLearnsToCode

Diff for: README.md

@@ -914,7 +914,7 @@
 | 3151 | [Special Array I](https://leetcode.com/problems/special-array-i)                                                                                                       |                                                                                        [![Java](assets/java.png)](src/SpecialArrayI.java)                                                                                        |                                                                                                                                   |
 | 3158 | [Find the XOR of Numbers Which Appear Twice](https://leetcode.com/problems/find-the-xor-of-numbers-which-appear-twice)                                                 |                                                                             [![Java](assets/java.png)](src/FindTheXOROfNumbersWhichAppearTwice.java)                                                                             |                                                                                                                                   |
 | 3162 | [Find the Number of Good Pairs I](https://leetcode.com/problems/find-the-number-of-good-pairs-i)                                                                       |                                                                                  [![Java](assets/java.png)](src/FindTheNumberOfGoodPairsI.java)                                                                                  |                                                                                                                                   |
-| 3168 | [Minimum Number of Chairs in a Waiting Room](https://leetcode.com/problems/minimum-number-of-chairs-in-a-waiting-room)                                                 |                                                                                                                                                                                                                                  |                                                                                                                                   |
+| 3168 | [Minimum Number of Chairs in a Waiting Room](https://leetcode.com/problems/minimum-number-of-chairs-in-a-waiting-room)                                                 |                                                                             [![Java](assets/java.png)](src/MinimumNumberOfChairsInAWaitingRoom.java)                                                                             |                                                                                                                                   |
 | 3173 | [Bitwise OR of Adjacent Elements](https://leetcode.com/problems/bitwise-or-of-adjacent-elements)                                                                       |                                                                                                                                                                                                                                  |                                                                                                                                   |
 | 3174 | [Clear Digits](https://leetcode.com/problems/clear-digits)                                                                                                             |                                                                                                                                                                                                                                  |                                                                                                                                   |
 | 3178 | [Find the Child Who Has the Ball After K Seconds](https://leetcode.com/problems/find-the-child-who-has-the-ball-after-k-seconds)                                       |                                                                                                                                                                                                                                  |                                                                                                                                   |

Diff for: src/MinimumNumberOfChairsInAWaitingRoom.java

@@ -0,0 +1,18 @@
+// https://leetcode.com/problems/minimum-number-of-chairs-in-a-waiting-room
+// T: O(N)
+// S: O(1)
+
+public class MinimumNumberOfChairsInAWaitingRoom {
+    public int minimumChairs(String s) {
+        int minChairs = 0;
+        for (int i = 0, sum = 0 ; i < s.length() ; i++) {
+            if (s.charAt(i) == 'E') {
+                sum++;
+            } else {
+                sum--;
+            }
+            minChairs = Math.max(minChairs, sum);
+        }
+        return minChairs;
+    }
+}