Add coin-change solution in TypeScript

Author: Jeehay28

coin-change/Jeehay28.ts

@@ -0,0 +1,72 @@
+// Approach 2: Dynamic Programming
+// // Time Complexity: O(amout * n), where n is the number of coins
+// // Space Complexity: O(amount)
+
+function coinChange(coins: number[], amount: number): number {
+
+    // input: coins = [2, 3, 5], amount = 7
+
+    // initial state dp
+    // 0: 0 
+    // 1: amount + 1 = 8
+    // 2: 8
+    // 3: 8
+    // 4: 8
+    // 5: 8
+    // 6: 8
+    // 7: 8
+
+    // using coin 2
+    // 0: 0 
+    // 1: 8
+    // 2: 8 -> 8 vs dp[2-2] + 1 = 1 -> 1 
+    // 3: 8 -> 8 vs dp[3-2] + 1 = 9 -> 8 
+    // 4: 8 -> 8 vs dp[4-2] + 1 = 2 -> 2
+    // 5: 8 -> 8 vs dp[5-2] + 1 = 9 -> 8
+    // 6: 8 -> 8 vs dp[6-2] + 1 = 3 -> 3
+    // 7: 8 -> 8 vs dp[7-2] + 1 = 9 -> 8
+
+    const dp = Array.from({ length: amount + 1 }, () => amount + 1);
+    dp[0] = 0
+
+    for (const coin of coins) {
+        for (let currentTotal = coin; currentTotal <= amount; currentTotal++) {
+            dp[currentTotal] = Math.min(dp[currentTotal - coin] + 1, dp[currentTotal])
+        }
+    }
+  
+    return dp[amount] > amount ? -1 : dp[amount]
+};
+
+
+// // Approach 1: BFS Traversal
+// // Time Complexity: O(amout * n), where n is the number of coins
+// // Space Complexity: O(amount)
+
+// function coinChange(coins: number[], amount: number): number {
+//   // queue: [[number of coints, current total]]
+//   let queue = [[0, 0]];
+//   let visited = new Set();
+
+//   while (queue.length > 0) {
+//     const [cnt, total] = queue.shift()!;
+
+//     if (total === amount) {
+//       return cnt;
+//     }
+
+//     if (visited.has(total)) {
+//       continue;
+//     }
+//     visited.add(total);
+
+//     for (const coin of coins) {
+//       if (total + coin <= amount) {
+//         queue.push([cnt + 1, total + coin]);
+//       }
+//     }
+//   }
+
+//   return -1;
+// }
+