diff --git a/HamSungJun/DynamicProgramming/Solution_1137.ts b/HamSungJun/DynamicProgramming/Solution_1137.ts
new file mode 100644
index 0000000..ab7945e
--- /dev/null
+++ b/HamSungJun/DynamicProgramming/Solution_1137.ts
@@ -0,0 +1,15 @@
+function tribonacci (n: number): number {
+  if (n <= 1) return n
+  if (n === 2) return 1
+  let t0 = 0
+  let t1 = 1
+  let t2 = 1
+  let acc = 0
+  for (let i = 3; i <= n; i++) {
+    acc = t2 + t1 + t0
+    t0 = t1
+    t1 = t2
+    t2 = acc
+  }
+  return acc
+};
diff --git a/HamSungJun/DynamicProgramming/Solution_338.ts b/HamSungJun/DynamicProgramming/Solution_338.ts
new file mode 100644
index 0000000..616f0f7
--- /dev/null
+++ b/HamSungJun/DynamicProgramming/Solution_338.ts
@@ -0,0 +1,14 @@
+function countBits (n: number): number[] {
+  if (n === 0) return [0]
+  const DP: number[] = new Array(n + 1)
+  DP[0] = 0
+  DP[1] = 1
+  for (let i = 2; i <= n; i++) {
+    if (Number.isInteger(Math.sqrt(i / 2))) {
+      DP[i] = 1
+    } else {
+      DP[i] = DP[Math.floor(i / 2)] + (i % 2 === 0 ? 0 : 1)
+    }
+  }
+  return DP
+};
diff --git a/HamSungJun/DynamicProgramming/Solution_746.ts b/HamSungJun/DynamicProgramming/Solution_746.ts
new file mode 100644
index 0000000..334d331
--- /dev/null
+++ b/HamSungJun/DynamicProgramming/Solution_746.ts
@@ -0,0 +1,10 @@
+function minCostClimbingStairs (cost: number[]): number {
+  const DP = new Array(cost.length).fill(0)
+  for (let i = 2; i < cost.length; i++) {
+    DP[i] = Math.min(
+      DP[i - 1] + cost[i - 1],
+      DP[i - 2] + cost[i - 2]
+    )
+  }
+  return DP[DP.length - 1]
+};
diff --git a/HamSungJun/Solution_1281.ts b/HamSungJun/Solution_1281.ts
new file mode 100644
index 0000000..a883e42
--- /dev/null
+++ b/HamSungJun/Solution_1281.ts
@@ -0,0 +1,11 @@
+function subtractProductAndSum (n: number): number {
+  let pAcc = 1
+  let sAcc = 0
+  while (n > 0) {
+    const nextDigit = (n % 10)
+    pAcc *= nextDigit
+    sAcc += nextDigit
+    n = Math.floor(n / 10)
+  }
+  return pAcc - sAcc
+};
diff --git a/HamSungJun/Solution_1342.ts b/HamSungJun/Solution_1342.ts
new file mode 100644
index 0000000..8e009da
--- /dev/null
+++ b/HamSungJun/Solution_1342.ts
@@ -0,0 +1,12 @@
+function numberOfSteps (num: number): number {
+  let stepCount = 0
+  while (num > 0) {
+    if (num % 2 === 0) {
+      num /= 2
+    } else {
+      num -= 1
+    }
+    stepCount += 1
+  }
+  return stepCount
+};
diff --git a/HamSungJun/Solution_1720.ts b/HamSungJun/Solution_1720.ts
new file mode 100644
index 0000000..e1bede9
--- /dev/null
+++ b/HamSungJun/Solution_1720.ts
@@ -0,0 +1,8 @@
+function decode (encoded: number[], first: number): number[] {
+  const decoded = new Array(encoded.length + 1)
+  decoded[0] = first
+  for (let i = 1; i < decoded.length; i++) {
+    decoded[i] = decoded[i - 1] ^ encoded[i - 1]
+  }
+  return decoded
+};