Update 数组相关.md

blogs/Algorithm/剑指 Offer/数组相关.md

@@ -17,6 +17,36 @@ class Solution {
 }
 ```
 
+```java
+class Solution {
+
+    public int findRepeatNumber(int[] nums) {
+        Arrays.sort(nums);
+        for (int i = 0; i < nums.length - 1; i++) {
+            if (nums[i] == nums[i + 1]) {
+                return nums[i];
+            }
+        }
+        return -1;
+    }
+}
+```
+
+```java
+class Solution {
+
+    public int findRepeatNumber(int[] nums) {
+        HashSet<Integer> set = new HashSet<>();
+        for (int i : nums) {
+            if (!set.add(i)) {
+                return i;
+            }
+        }
+        return -1;
+    }
+}
+```
+
 [04. 二维数组中的查找](https://leetcode-cn.com/problems/er-wei-shu-zu-zhong-de-cha-zhao-lcof/)
 
 ```java