[LEET-3491] add 3491

Author: fishercoder1534

paginated_contents/algorithms/4th_thousand/README.md

@@ -1,6 +1,7 @@
 | #    | Title                                                                                                                                                               | Solutions                                                                                                                         | Video                                                                         | Difficulty | Tag                                                                  
 |------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------|------------|----------------------------------------------------------------------
 | 3502 | [Minimum Cost to Reach Every Position](https://leetcode.com/problems/minimum-cost-to-reach-every-position/)                                                               | [Java](https://github.com/fishercoder1534/Leetcode/blob/master/src/main/java/com/fishercoder/solutions/fourththousand/_3502.java) |                                                                               | Easy       |
+| 3491 | [Phone Number Prefix](https://leetcode.com/problems/phone-number-prefix/)                                                               | [Java](https://github.com/fishercoder1534/Leetcode/blob/master/src/main/java/com/fishercoder/solutions/fourththousand/_3491.java) |                                                                               | Easy       |
 | 3471 | [Find the Largest Almost Missing Integer](https://leetcode.com/problems/find-the-largest-almost-missing-integer/)                                                               | [Java](https://github.com/fishercoder1534/Leetcode/blob/master/src/main/java/com/fishercoder/solutions/fourththousand/_3471.java) |                                                                               | Easy       |
 | 3402 | [Minimum Operations to Make Columns Strictly Increasing](https://leetcode.com/problems/minimum-operations-to-make-columns-strictly-increasing/)                                                               | [Java](https://github.com/fishercoder1534/Leetcode/blob/master/src/main/java/com/fishercoder/solutions/fourththousand/_3402.java) |                                                                               | Easy       |
 | 3396 | [Minimum Number of Operations to Make Elements in Array Distinct](https://leetcode.com/problems/minimum-number-of-operations-to-make-elements-in-array-distinct/)                                                               | [Java](https://github.com/fishercoder1534/Leetcode/blob/master/src/main/java/com/fishercoder/solutions/fourththousand/_3396.java) |                                                                               | Easy       |

src/main/java/com/fishercoder/solutions/fourththousand/_3491.java

@@ -0,0 +1,16 @@
+package com.fishercoder.solutions.fourththousand;
+
+public class _3491 {
+    public static class Solution1 {
+        public boolean phonePrefix(String[] numbers) {
+            for (int i = 0; i < numbers.length; i++) {
+                for (int j = 0; j < numbers.length; j++) {
+                    if (i != j && numbers[i].startsWith(numbers[j])) {
+                        return false;
+                    }
+                }
+            }
+            return true;
+        }
+    }
+}

src/test/java/com/fishercoder/fourththousand/_3491Test.java

@@ -0,0 +1,21 @@
+package com.fishercoder.fourththousand;
+
+import com.fishercoder.solutions.fourththousand._3491;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class _3491Test {
+    private _3491.Solution1 solution1;
+
+    @BeforeEach
+    public void setup() {
+        solution1 = new _3491.Solution1();
+    }
+
+    @Test
+    public void test1() {
+        assertEquals(true, solution1.phonePrefix(new String[]{"1", "2", "4", "3"}));
+    }
+}