completed DP 1 course

CoinChange.java

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+class Solution {
+    // TC - O(n * m)
+    // SC - O(n * m)
+    public int coinChange(int[] coins, int amount) {
+        int n = coins.length;
+        int m = amount;
+
+        //initialize dp array to store the min required coins, the first row is initialized to maximum value for comparison purposes
+        int[][] dp = new int[n + 1][m + 1];
+        for (int j = 0; j <= m; j++) {
+            dp[0][j] = amount + 1;
+        }
+
+        for (int i = 1; i <= n; i++) {
+           for (int j = 1; j <= m; j++) {
+                // if the amount at current index is less than the coins[i - 1] value (if amount is 2 and coind value is 5) then we just take value from the row
+                if (j < coins[i - 1]) {
+                    dp[i][j] = dp[i-1][j];
+                } else {
+                    // else we calculate minimum of the value row above has and the total of value at index position
+                    dp[i][j] = Math.min(dp[i-1][j], dp[i][j - coins[i - 1]] + 1);
+                }
+            } 
+        }
+
+        if (dp[n][m] > amount) {
+            return -1;
+        }
+
+        return dp[n][m];
+    }
+}

HouseRobber.java

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+class Solution {
+    //SC - O(1)
+    //TC - O(n)
+    public int rob(int[] nums) {
+        int n = nums.length;
+        int prev = 0;
+        int curr = nums[0];
+
+        for (int i = 1; i < n; i++) {
+            int temp = curr; // store curr value in prev
+            curr = Math.max(curr, prev + nums[i]); // calc maximum of robbing the current house (prev + nums[i]) and the value of previous house (curr)
+            prev = temp;
+        }
+
+        return curr;
+    }
+}