solves find greatest common divisor of array

Author: anishLearnsToCode

Diff for: README.md

@@ -474,7 +474,7 @@
 | 1967 | [Number of Strings That Appear as Substrings in Word](https://leetcode.com/problems/number-of-strings-that-appear-as-substrings-in-word)                  |                                                   [![Java](assets/java.png)](src/NumberOfStringsThatAppearAsSubstringsInWord.java)                                                   |                                                                                                                                   |
 | 1971 | [Find if Path Exists in Graph](https://leetcode.com/problems/find-if-path-exists-in-graph)                                                                |                                                             [![Java](assets/java.png)](src/FindIfPathExistsInGraph.java)                                                             |                                                                                                                                   |
 | 1974 | [Minimum Time to Type Word Using Special Typewriter](https://leetcode.com/problems/minimum-time-to-type-word-using-special-typewriter)                    |                                                   [![Java](assets/java.png)](src/MinimumTimeToTypeWordUsingSpecialTypewriter.java)                                                   |                                                                                                                                   |
-| 1979 | [Find Greatest Common Divisor of Array](https://leetcode.com/problems/find-greatest-common-divisor-of-array)                                              |                                                                                                                                                                                      |                                                                                                                                   |
+| 1979 | [Find Greatest Common Divisor of Array](https://leetcode.com/problems/find-greatest-common-divisor-of-array)                                              |                                                        [![Java](assets/java.png)](src/FindGreatestCommonDivisorOfArray.java)                                                         |                                                                                                                                   |
 | 1984 | [Minimum Difference Between Highest and Lowest of K Scores](https://leetcode.com/problems/minimum-difference-between-highest-and-lowest-of-k-scores)      |                                                                                                                                                                                      |                                                                                                                                   |
 | 1991 | [Find the Middle Index in Array](https://leetcode.com/problems/find-the-middle-index-in-array)                                                            |                                                                                                                                                                                      |                                                                                                                                   |
 | 1995 | [Count Special Quadruplets](https://leetcode.com/problems/count-special-quadruplets)                                                                      |                                                                                                                                                                                      |                                                                                                                                   |

Diff for: src/FindGreatestCommonDivisorOfArray.java

@@ -0,0 +1,18 @@
+// https://leetcode.com/problems/find-greatest-common-divisor-of-array
+// T: O(N)
+// S: O(1)
+
+import java.util.Arrays;
+
+public class FindGreatestCommonDivisorOfArray {
+    public int findGCD(int[] nums) {
+        return gcd(
+                Arrays.stream(nums).max().getAsInt(),
+                Arrays.stream(nums).min().getAsInt()
+        );
+    }
+
+    private int gcd(int a, int b) {
+        return b == 0 ? a : gcd(b, a % b);
+    }
+}