Add coin change solution

Author: hyunjung-choi

coin-change/hyunjung-choi.kt

@@ -0,0 +1,21 @@
+/**
+ * 시간복잡도: O(amount × coins.length)
+ * 공간복잡도: O(amount)
+ */
+
+class Solution {
+    fun coinChange(coins: IntArray, amount: Int): Int {
+        val dp = IntArray(amount + 1) { Int.MAX_VALUE }
+        dp[0] = 0
+
+        for (i in 1..amount) {
+            for (coin in coins) {
+                if (i - coin >= 0 && dp[i - coin] != Int.MAX_VALUE) {
+                    dp[i] = minOf(dp[i], dp[i - coin] + 1)
+                }
+            }
+        }
+
+        return if (dp[amount] == Int.MAX_VALUE) -1 else dp[amount]
+    }
+}