dp07

198. 打家劫舍

class Solution {
public:
    int rob(vector<int>& nums) {    
        if (nums.size() == 0) return 0;
        if (nums.size() == 1) return nums[0];
        vector<int> dp(nums.size(), 0);
        dp[0] = nums[0];      
        dp[1] = max(nums[1], nums[0]);
        for (int i = 2; i < nums.size(); i++){
            dp[i] = max(dp[i - 1], dp[i - 2] + nums[i]);
        }
        return dp[nums.size() - 1];

    }
};

213.打家劫舍II

class Solution {
public:
    int robRange(vector<int>& nums, int start, int end) {
        if (end == start) return nums[start];
        vector<int> dp(nums.size());
        dp[start] = nums[start];
        dp[start + 1] = max(nums[start], nums[start + 1]);
        for (int i = start + 2; i <= end; i++) {
            dp[i] = max(dp[i - 2] + nums[i], dp[i - 1]);
        }
        return dp[end];
    }

    int rob(vector<int>& nums) {
        if (nums.size() == 1) return nums[0];
        int result = max(robRange(nums, 0, nums.size() - 2), robRange(nums, 1, nums.size() - 1));
        return result;

    }
};

337.打家劫舍III

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
 *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
 * };
 */
class Solution {
public:
    vector<int> robTree(TreeNode* node) {
        if (node == nullptr) return {0, 0};
        vector<int> leftdp = robTree(node -> left);
        vector<int> rightdp = robTree(node -> right);
        int val1 = max(leftdp[0], leftdp[1]) + max(rightdp[0], rightdp[1]);
        int val2 = node -> val + leftdp[0] + rightdp[0];

        return {val1, val2};
    }
    int rob(TreeNode* root) {
        vector<int> dp = robTree(root);
        return max(dp[0], dp[1]);
    }
};