diff --git a/src/problem/mod.rs b/src/problem/mod.rs
index 27b880f..8166919 100644
--- a/src/problem/mod.rs
+++ b/src/problem/mod.rs
@@ -202,4 +202,5 @@ mod p120_triangle;
 mod p64_minimum_path_sum;
 mod p63_unique_paths_ii;
 mod p97_interleaving_string;
-mod p72_edit_distance;
\ No newline at end of file
+mod p72_edit_distance;
+mod p123_best_time_to_buy_and_sell_stock_iii;
\ No newline at end of file
diff --git a/src/problem/p123_best_time_to_buy_and_sell_stock_iii.rs b/src/problem/p123_best_time_to_buy_and_sell_stock_iii.rs
new file mode 100644
index 0000000..0858fd8
--- /dev/null
+++ b/src/problem/p123_best_time_to_buy_and_sell_stock_iii.rs
@@ -0,0 +1,37 @@
+/**
+ * [123] Best Time to Buy and Sell Stock III
+ */
+pub struct Solution {}
+
+
+// submission codes start here
+
+impl Solution {
+    pub fn max_profit(prices: Vec<i32>) -> i32 {
+        let n = prices.len();
+        let (mut buy1, mut sell1) = (-prices[0], 0);
+        let (mut buy2, mut sell2) = (-prices[0], 0);
+
+        for i in 1..n {
+            buy1 = buy1.max(-prices[i]);
+            sell1 = sell1.max(buy1 + prices[i]);
+            buy2 = buy2.max(sell1 - prices[i]);
+            sell2 = sell2.max(buy2 + prices[i]);
+        }
+
+        sell2
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_123() {
+        assert_eq!(4, Solution::max_profit(vec![1, 2, 3, 4, 5]));
+        assert_eq!(6, Solution::max_profit(vec![3, 3, 5, 0, 0, 3, 1, 4]));
+    }
+}