#198

House Robber

MediumDynamic Programming

You are a robber planning to rob houses along a street. Each house has some money, but adjacent houses have connected alarms, so robbing two adjacent houses triggers the police.

Given an integer array nums of the money in each house, return the maximum amount you can rob without alerting the police.

Example

nums = [1, 2, 3, 1]     => 4   // rob house 0 and 2
nums = [2, 7, 9, 3, 1]  => 12  // rob houses 0, 2, 4

Implement

function Rob(nums: int[]) -> int

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BAML docs

baml describe

Search the BAML stdlib (260 symbols). Try a type, function, or method name.

Basics

let x = 0;

mutable binding

let nums: int[] = [];

typed binding

function Add(a: int, b: int) -> int {
  return a + b;
}

Control flow

if (x > 0) {
  ...
} else {
  ...
}

while (i < n) {
  i += 1;
}

for (x in nums) {
  ...
}

iterate values

break;   continue;   return v;

Arrays

nums.length()

nums[i]

read (0-indexed)

nums[i] = v

write

nums.push(x)

nums.pop()

returns T? (optional)

nums.slice(a, b)   nums.reverse()

nums.sort_by_key(k)   nums.sort_by(cmp)

returns a sorted copy (no bare .sort())

Maps (use string keys)

let m: map<string, int> = {};

m.set("a", 1);

m.get("a")

returns int? (null if absent)

m.has("a")   m.keys()

m.set(n.to_string(), true);

int keys are unsupported: convert to string

Strings

s.length()

number of characters

s.char_at(i)   s.substring(a, b)

s.split(",")   s.to_lower_case()

c.is_alphanumeric()   c == "a"

Numbers

a / b

integer division

a % b

remainder

x.abs()   x.pow(e)   x.min(y)   x.max(y)

x & 1   x >> 1   x << 2   x ^ y

bitwise ops

n.to_string()

value to string

int.parse(s)

string to int

Optionals & null

let node: ListNode? = null;

if (x == null) {
  return 0;
}
// x is non-null below

guard-and-return narrows the type

Classes

class ListNode {
  val int
  next ListNode?
}

ListNode { val: 1, next: null }

construct with { }

node.val   node.next