House Robber solution

Author: HoonDongKang

house-robber/HoonDongKang.ts

@@ -0,0 +1,54 @@
+/**
+ * [Problem]: [198] House Robber
+ * (https://leetcode.com/problems/house-robber/description/)
+ */
+function rob(nums: number[]): number {
+    // 시간 복잡도 O(2^n)
+    // 공간 복잡도 O(n)
+    // 시간 초과
+    function recursionFunc(nums: number[]): number {
+        function getMax(start: number): number {
+            if (nums.length - 1 < start) return 0;
+            return Math.max(nums[start] + getMax(start + 2), getMax(start + 1));
+        }
+
+        return getMax(0);
+    }
+
+    // 메모이제이션
+    // 시간복잡도 O(n)
+    // 공간복잡도 O(n)
+    function memoizationFunc(nums: number[]): number {
+        let memoArr = new Array(nums.length).fill(-1);
+        function getMax(start: number): number {
+            if (nums.length - 1 < start) return 0;
+            if (memoArr[start] !== -1) return memoArr[start];
+
+            memoArr[start] = Math.max(nums[start] + getMax(start + 2), getMax(start + 1));
+
+            return memoArr[start];
+        }
+
+        return getMax(0);
+    }
+
+    // DP
+    // 시간복잡도 O(n)
+    // 공간복잡도 O(1)
+    function dpSolution(nums: number[]): number {
+        if (nums.length === 1) return nums[0];
+
+        let prev2 = 0;
+        let prev1 = 0;
+
+        for (let num of nums) {
+            let current = Math.max(prev1, prev2 + num);
+            prev2 = prev1;
+            prev1 = current;
+        }
+
+        return prev1;
+    }
+
+    return dpSolution(nums);
+}