house robber solution

Author: nancyel

house-robber/nancyel.ts

@@ -0,0 +1,22 @@
+/**
+ * time complexity: O(n) - iterate over a loop
+ * space complexity: O(n) - dp array
+ *
+ * comment: initial naive implementation: simple odd/even alternation, which may return result that is "accidentally correct."
+ */
+function rob(nums: number[]): number {
+  // early return
+  if (nums.length === 0) return 0;
+  if (nums.length === 1) return nums[0];
+
+  const dp: number[] = new Array(nums.length);
+  dp[0] = nums[0];
+  dp[1] = Math.max(nums[0], nums[1]);
+
+  for (let i = 2; i < nums.length; i++) {
+    // select either 1) current + best from 2 houses ago or 2) skip current, best from previous
+    dp[i] = Math.max(nums[i] + dp[i - 2], dp[i - 1]);
+  }
+
+  return dp[nums.length - 1]; // max money from all houses
+}