diff --git a/src/main/java/leetcode/editor/cn/SingleElementInASortedArray.java b/src/main/java/leetcode/editor/cn/SingleElementInASortedArray.java
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+//给定一个只包含整数的有序数组，每个元素都会出现两次，唯有一个数只会出现一次，找出这个数。 
+//
+// 
+//
+// 示例 1: 
+//
+// 
+//输入: nums = [1,1,2,3,3,4,4,8,8]
+//输出: 2
+// 
+//
+// 示例 2: 
+//
+// 
+//输入: nums =  [3,3,7,7,10,11,11]
+//输出: 10
+// 
+//
+// 
+//
+// 
+//
+// 提示: 
+//
+// 
+// 1 <= nums.length <= 105 
+// 0 <= nums[i] <= 105 
+// 
+//
+// 
+//
+// 进阶: 采用的方案可以在 O(log n) 时间复杂度和 O(1) 空间复杂度中运行吗？ 
+// Related Topics 数组 二分查找 
+// 👍 256 👎 0
+
+package leetcode.editor.cn;
+
+//540:有序数组中的单一元素
+class SingleElementInASortedArray {
+    public static void main(String[] args) {
+        //测试代码
+        Solution solution = new SingleElementInASortedArray().new Solution();
+    }
+
+    //力扣代码
+    //leetcode submit region begin(Prohibit modification and deletion)
+    class Solution {
+        public int singleNonDuplicate(int[] nums) {
+            for (int i = 0; i < nums.length; i = i + 2) {
+                if (i + 1 == nums.length || nums[i] != nums[i + 1]) {
+                    return nums[i];
+                }
+            }
+            return 0;
+        }
+    }
+//leetcode submit region end(Prohibit modification and deletion)
+
+}
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diff --git a/src/main/java/leetcode/editor/cn/SingleElementInASortedArray.md b/src/main/java/leetcode/editor/cn/SingleElementInASortedArray.md
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+<p>给定一个只包含整数的有序数组，每个元素都会出现两次，唯有一个数只会出现一次，找出这个数。</p>
+
+<p> </p>
+
+<p><strong>示例 1:</strong></p>
+
+<pre>
+<strong>输入:</strong> nums = [1,1,2,3,3,4,4,8,8]
+<strong>输出:</strong> 2
+</pre>
+
+<p><strong>示例 2:</strong></p>
+
+<pre>
+<strong>输入:</strong> nums =  [3,3,7,7,10,11,11]
+<strong>输出:</strong> 10
+</pre>
+
+<p> </p>
+
+<p><meta charset="UTF-8" /></p>
+
+<p><strong>提示:</strong></p>
+
+<ul>
+	<li><code>1 <= nums.length <= 10<sup>5</sup></code></li>
+	<li><code>0 <= nums[i] <= 10<sup>5</sup></code></li>
+</ul>
+
+<p> </p>
+
+<p><strong>进阶:</strong> 采用的方案可以在 <code>O(log n)</code> 时间复杂度和 <code>O(1)</code> 空间复杂度中运行吗？</p>
+<div><div>Related Topics</div><div><li>数组</li><li>二分查找</li></div></div>\n<div><li>👍 256</li><li>👎 0</li></div>
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