DP-2 Solution

CoinChange2.java

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+//Time Complexity: O(n * amount) where n is the number of coins
+//Space Complexity: O(n * amount) where n is the number of coins
+public class CoinChange2 {
+    int[][] comb;
+    public int change(int amount, int[] coins) {
+        comb = new int[coins.length + 1][amount + 1];
+        for (int i = 0; i <= coins.length; i++) comb[i][amount] = 1;
+        for (int i = coins.length - 1; i >= 0; i--) {
+            for (int amt = amount; amt >= 0; amt--) {
+                comb[i][amt] = comb[i + 1][amt];
+                if (coins[i] + amt <= amount) {
+                    comb[i][amt] += comb[i][amt + coins[i]];
+
+
+                }
+
+            }
+        }
+        return comb[0][0];
+    }
+}

PaintHouse.java

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+//Time Complexity : O(n)
+//Space Complexity : O(n)
+public class PaintHouse {
+    public int minCost(int[][] costs) {
+        int m = costs.length;
+        int n = costs[0].length;
+
+        int[][] dp = new int[m][n];
+
+        dp[0][0] = costs[0][0];
+        dp[0][1] = costs[0][1];
+        dp[0][2] = costs[0][2];
+
+        for(int i = 1; i < m; i++) {
+            dp[i][0] = costs[i][0] + Math.min(dp[i-1][1], dp[i-1][2]);
+            dp[i][1] = costs[i][1] + Math.min(dp[i-1][0], dp[i-1][2]);
+            dp[i][2] = costs[i][2] + Math.min(dp[i-1][0], dp[i-1][1]);
+        }
+
+        return Math.min(dp[m-1][0], Math.min(dp[m-1][1], dp[m-1][2]));
+
+    }
+}