diff --git a/Algorithms/Easy/645_SetMismatch/Solution.cpp b/Algorithms/Easy/645_SetMismatch/Solution.cpp
new file mode 100644
index 0000000..4debef3
--- /dev/null
+++ b/Algorithms/Easy/645_SetMismatch/Solution.cpp
@@ -0,0 +1,22 @@
+class Solution {
+public:
+    vector<int> findErrorNums(vector<int>& nums) {
+        int n = nums.size(), sumXor = 0;
+        int mark[n + 1];
+        memset(mark, 0, sizeof(mark));
+        vector<int> ans;
+        
+        for (int i = 0; i < n; i++) {
+            sumXor ^= nums[i] ^ (i + 1);
+            
+            if (mark[nums[i]] == 1) {
+                ans.push_back(nums[i]);
+            }
+            
+            mark[nums[i]]++;
+        }
+        
+        ans.push_back(sumXor ^ ans[0]);
+        return ans;
+    }
+};
\ No newline at end of file
diff --git a/Algorithms/Easy/645_SetMismatch/Solution.java b/Algorithms/Easy/645_SetMismatch/Solution.java
new file mode 100644
index 0000000..6e20f13
--- /dev/null
+++ b/Algorithms/Easy/645_SetMismatch/Solution.java
@@ -0,0 +1,20 @@
+class Solution {
+    public int[] findErrorNums(int[] nums) {
+        int n = nums.length, sumXor = 0;
+        int mark[] = new int[n + 1];
+        int ans[] = new int[2];
+        
+        for (int i = 0; i < n; i++) {
+            sumXor ^= nums[i] ^ (i + 1);
+            
+            if (mark[nums[i]] == 1) {
+                ans[0] = nums[i];
+            }
+            
+            mark[nums[i]]++;
+        }
+        
+        ans[1] = sumXor ^ ans[0];
+        return ans;
+    }
+}
\ No newline at end of file