House Robber: money = [2, 7, 9, 3, 1]
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dp[k] = best total using only the first k houses
k      [0, 1, 2, 3, 4, 5]
dp[k]  [0, 2, 7, 11, 11, 12]

k=1  house worth 2: skip = dp[0] = 0, take = dp[0] + 2 = 2  ->  dp[1] = 2
k=2  house worth 7: skip = dp[1] = 2, take = dp[0] + 7 = 7  ->  dp[2] = 7
k=3  house worth 9: skip = dp[2] = 7, take = dp[1] + 9 = 11  ->  dp[3] = 11
k=4  house worth 3: skip = dp[3] = 11, take = dp[2] + 3 = 10  ->  dp[4] = 11
k=5  house worth 1: skip = dp[4] = 11, take = dp[3] + 1 = 12  ->  dp[5] = 12

answer = 12 (houses worth 2, 9 and 1)
