Coin Change

coin-change/forest000014.java

@@ -0,0 +1,28 @@
+/* 
+Time Complexity: O(coins.length * amount)
+Space Complexity: O(amount)
+
+1 ~ i-1원까지의 최적해를 알고 있다면, i원의 최적해를 구할 때 coins 배열 iteration으로 구할 수 있음
+*/
+class Solution {
+    public int coinChange(int[] coins, int amount) {
+        int c = coins.length;
+
+        int[] dp = new int[amount + 1];
+        Arrays.fill(dp, 99999);
+        dp[0] = 0;
+
+        for (int i = 1; i <= amount; i++) {
+            for (int j = 0; j < c; j++) {
+                if (i - coins[j] < 0) {
+                    continue;
+                }
+                if (dp[i - coins[j]] >= 0 && dp[i - coins[j]] + 1 < dp[i]) {
+                    dp[i] = dp[i - coins[j]] + 1;
+                }
+            }
+        }
+
+        return dp[amount] == 99999 ? -1 : dp[amount];
+    }
+}