代码随想录算法训练营第四十四天 | 198. 打家劫舍 213. 打家劫舍 II 337. 打家劫舍 III

198. 打家劫舍

题目链接：LeetCode
文档讲解：代码随想录
状态：AC

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Java代码：

class Solution {
    public int rob(int[] nums) {
        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(dp[i - 1], dp[i - 2] + nums[i]);
        }
        return dp[nums.length - 1];
    }
}

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213. 打家劫舍 II

题目链接：LeetCode
文档讲解：代码随想录
状态：AC

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Java代码：

class Solution {
    public int rob(int[] nums) {
        int len = nums.length;
        if (len == 1) {
            return nums[0];
        }
        int res1 = robHelper(nums, 1, len - 1);
        int res2 = robHelper(nums, 0, len - 2);
        return Math.max(res1, res2);
    }

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

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337. 打家劫舍 III

题目链接：LeetCode
文档讲解：代码随想录
状态：AC

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Java代码：

class Solution {
    public int rob(TreeNode root) {
        int[] res = robTree(root);
        return Math.max(res[0], res[1]);
    }

    // 0 偷
    // 1 不偷
    int[] robTree(TreeNode root) {
        if (root == null) {
            return new int[]{0, 0};
        }
        int[] left = robTree(root.left);
        int[] right = robTree(root.right);

        int robFalse = Math.max(left[0], left[1]) + Math.max(right[0], right[1]);
        int robTrue = root.val + left[0] + right[0];
        return new int[]{robFalse, robTrue};
    }
}