public int rob(int[] nums) {
        if (nums == null || nums.length == 0) return 0;
        if (nums.length == 1) return nums[0];

        int[] dp = new int[nums.length];
        dp[0] = nums[0]; dp[1] = Math.max(nums[0], nums[1]);
        for (int i = 2; i < nums.length; ++i) {
            dp[i] = Math.max(nums[i] + dp[i - 2], dp[i - 1]);
        }
        return dp[dp.length - 1];
    }