diff --git a/src/main/java/leetcode/editor/cn/MissingNumberLcci.java b/src/main/java/leetcode/editor/cn/MissingNumberLcci.java
new file mode 100644
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+++ b/src/main/java/leetcode/editor/cn/MissingNumberLcci.java
@@ -0,0 +1,40 @@
+//数组nums包含从0到n的所有整数，但其中缺了一个。请编写代码找出那个缺失的整数。你有办法在O(n)时间内完成吗？ 
+//
+// 注意：本题相对书上原题稍作改动 
+//
+// 示例 1： 
+//
+// 输入：[3,0,1]
+//输出：2 
+//
+// 
+//
+// 示例 2： 
+//
+// 输入：[9,6,4,2,3,5,7,0,1]
+//输出：8
+// 
+// Related Topics 位运算 数组 哈希表 数学 排序 👍 57 👎 0
+
+package leetcode.editor.cn;
+
+//面试题 17.04:消失的数字
+public class MissingNumberLcci {
+    public static void main(String[] args) {
+        Solution solution = new MissingNumberLcci().new Solution();
+
+    }
+
+    //leetcode submit region begin(Prohibit modification and deletion)
+    class Solution {
+        public int missingNumber(int[] nums) {
+            int xor = nums.length;
+            for (int i = 0; i < nums.length; i++) {
+                xor ^= i ^ nums[i];
+            }
+            return xor;
+        }
+    }
+//leetcode submit region end(Prohibit modification and deletion)
+
+}
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diff --git a/src/main/java/leetcode/editor/cn/doc/content/MissingNumberLcci.md b/src/main/java/leetcode/editor/cn/doc/content/MissingNumberLcci.md
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+<p>数组<code>nums</code>包含从<code>0</code>到<code>n</code>的所有整数，但其中缺了一个。请编写代码找出那个缺失的整数。你有办法在O(n)时间内完成吗？</p>
+
+<p><strong>注意：</strong>本题相对书上原题稍作改动</p>
+
+<p><strong>示例 1：</strong></p>
+
+<pre><strong>输入：</strong>[3,0,1]
+<strong>输出：</strong>2</pre>
+
+<p>&nbsp;</p>
+
+<p><strong>示例 2：</strong></p>
+
+<pre><strong>输入：</strong>[9,6,4,2,3,5,7,0,1]
+<strong>输出：</strong>8
+</pre>
+<div><div>Related Topics</div><div><li>位运算</li><li>数组</li><li>哈希表</li><li>数学</li><li>排序</li></div></div><br><div><li>👍 57</li><li>👎 0</li></div>
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