代码随想录训练营day39|动态规划part7

打家劫舍

力扣题目链接

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

打家劫舍II

力扣题目链接

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

打家劫舍 III

力扣题目链接

class Solution {
public:
    int rob(TreeNode* root) {
        vector<int> result = robNode(root);
        return max(result[0], result[1]);
    }
    vector<int> robNode(TreeNode* root){
        if(!root)
            return {0,0};
        vector<int> l = robNode(root->left);
        vector<int> r = robNode(root->right);
        return {root->val + l[1] + r[1], max(l[0], l[1])+ max(r[0], r[1])};
    }
};