diff --git a/src/problem/mod.rs b/src/problem/mod.rs
index 4299d51..ddeb738 100644
--- a/src/problem/mod.rs
+++ b/src/problem/mod.rs
@@ -23,4 +23,5 @@ mod p2744_find_maximum_number_of_string_pairs;
 mod p2171_removing_minimum_number_of_magic_beans;
 mod p2809_minimum_time_to_make_array_sum_at_most_x;
 mod p2788_split_strings_by_separator;
-mod p410_split_array_largest_sum;
\ No newline at end of file
+mod p410_split_array_largest_sum;
+mod p670_maximum_swap;
\ No newline at end of file
diff --git a/src/problem/p670_maximum_swap.rs b/src/problem/p670_maximum_swap.rs
new file mode 100644
index 0000000..7193013
--- /dev/null
+++ b/src/problem/p670_maximum_swap.rs
@@ -0,0 +1,61 @@
+/**
+ * [670] Maximum Swap
+ */
+pub struct Solution {}
+
+
+// submission codes start here
+
+impl Solution {
+    pub fn maximum_swap(num: i32) -> i32 {
+        let mut num_array = Vec::new();
+        let mut num = num;
+
+        while num != 0 {
+            num_array.push(num % 10);
+            num = num / 10;
+        }
+        num_array.reverse();
+
+        for i in 0..num_array.len() {
+            let mut index = i;
+            for j in (i + 1)..num_array.len() {
+                if num_array[j] >= num_array[index] {
+                    index = j;
+                }
+            }
+
+            if index != i && num_array[index] != num_array[i] {
+                let temp = num_array[i];
+                num_array[i] = num_array[index];
+                num_array[index] = temp;
+                break;
+            }
+        }
+
+        let mut result = 0;
+
+        for i in num_array {
+            result += i;
+            result *= 10;
+        }
+        result /= 10;
+
+        result
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_670() {
+        assert_eq!(Solution::maximum_swap(2736), 7236);
+        assert_eq!(Solution::maximum_swap(9973), 9973);
+        assert_eq!(Solution::maximum_swap(98368), 98863);
+        assert_eq!(Solution::maximum_swap(1993), 9913);
+    }
+}