solves count the number of consistent strings

Author: anishLearnsToCode

README.md

@@ -414,7 +414,7 @@
 | 1668 | [Maximum Repeating Substring](https://leetcode.com/problems/maximum-repeating-substring)                                                                  |                                                            [![Java](assets/java.png)](src/MaximumRepeatingSubString.java)                                                            |                                                                                                                                   |
 | 1672 | [Richest Customer Wealth](https://leetcode.com/problems/richest-customer-wealth)                                                                          |                                                              [![Java](assets/java.png)](src/RichestCustomerWealth.java)                                                              |                                                                                                                                   |
 | 1678 | [Goal Parser Interpretation](https://leetcode.com/problems/goal-parser-interpretation)                                                                    |                                                            [![Java](assets/java.png)](src/GoalParserInterpretation.java)                                                             |                                                                                                                                   |
-| 1684 | [Count the Number of Consistent Strings](https://leetcode.com/problems/count-the-number-of-consistent-strings)                                            |                                                                                                                                                                                      |                                                                                                                                   |
+| 1684 | [Count the Number of Consistent Strings](https://leetcode.com/problems/count-the-number-of-consistent-strings)                                            |                                                        [![Java](assets/java.png)](src/CountTheNumberOfConsistentStrings.java)                                                        |                                                                                                                                   |
 | 1688 | [Count of Matches in Tournament](https://leetcode.com/problems/count-of-matches-in-tournament)                                                            |                                                                                                                                                                                      |                                                                                                                                   |
 | 1694 | [Reformat Phone Number](https://leetcode.com/problems/reformat-phone-number)                                                                              |                                                                                                                                                                                      |                                                                                                                                   |
 | 1700 | [Number of Students Unable to Eat Lunch](https://leetcode.com/problems/number-of-students-unable-to-eat-lunch)                                            |                                                                                                                                                                                      |                                                                                                                                   |

src/CountTheNumberOfConsistentStrings.java

@@ -0,0 +1,35 @@
+// T: O(allowed + words * word)
+// S: O(allowed)
+
+import java.util.HashSet;
+import java.util.Set;
+
+public class CountTheNumberOfConsistentStrings {
+    public int countConsistentStrings(String allowed, String[] words) {
+        final Set<Character> allowedCharacters = getCharacters(allowed);
+        int consistentStrings = 0;
+        for (String word :words) {
+            if (allCharsPresentIn(word, allowedCharacters)) {
+                consistentStrings++;
+            }
+        }
+        return consistentStrings;
+    }
+
+    private Set<Character> getCharacters(String string) {
+        final Set<Character> set = new HashSet<>();
+        for (int index = 0 ; index < string.length() ; index++) {
+            set.add(string.charAt(index));
+        }
+        return set;
+    }
+
+    private boolean allCharsPresentIn(String string, Set<Character> allowedChars) {
+        for (int index = 0 ; index < string.length() ; index++) {
+            if (!allowedChars.contains(string.charAt(index))) {
+                return false;
+            }
+        }
+        return true;
+    }
+}