solve: house robber

house-robber/GangBean.java

@@ -0,0 +1,28 @@
+class Solution {
+    public int rob(int[] nums) {
+        /**
+            r[0] = a[0]
+            r[1] = max(a[1], r[0])
+            r[2] = max(r[1], a[2] + r[0])
+            r[3] = max(r[2], a[3] + r[1])
+            ...
+            r[k] = max(r[k-1], a[k] + r[k-2]) O(1)
+        */
+        int[] r = new int[nums.length];
+
+        for (int i = 0; i < nums.length; i++) { // O(N)
+            if (i == 0) {
+                r[i] = nums[i];
+                continue;
+            }
+            if (i == 1) {
+                r[i] = Math.max(nums[i], r[i-1]);
+                continue;
+            }
+            r[i] = Math.max(r[i-1], nums[i] + r[i-2]);
+        }
+
+        return r[nums.length - 1];
+    }
+}
+