198. 打家劫舍

題目

思路與解法

class Solution {
public:int rob(vector<int>& nums) {// dp數組含義：//  考慮下標i（包括i）以內的房屋，最多可以偷竊的金額為dp[i]if (nums.size() == 0) return 0;if (nums.size() == 1) return nums[0];vector<int> dp(nums.size());dp[0] = nums[0];dp[1] = max(nums[0], nums[1]);for (int i = 2; i < nums.size(); i++) {dp[i] = max(dp[i - 2] + nums[i], dp[i - 1]);}return dp[nums.size() - 1];}
};

213. 打家劫舍 II

題目

思路與解法

class Solution {
public:int rob(vector<int>& nums) {if (nums.size() == 0) return 0;if (nums.size() == 1) return nums[0];int result1 = robRange(nums, 0, nums.size() - 2); // 情況二:不包含末尾int result2 = robRange(nums, 1, nums.size() - 1); // 情況三：不包含開頭return max(result1, result2);}// 198.打家劫舍的邏輯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];}
};

337. 打家劫舍 III

題目

思路與解法

/*** 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:int rob(TreeNode* root) {vector<int> result = robTree(root);return max(result[0], result[1]);}vector<int> robTree(TreeNode* cur){if(cur==NULL) return vector<int>{0,0};vector<int> left = robTree(cur->left);vector<int> right = robTree(cur->right);// 偷cur，那么就不能偷左右節點。int val1 = cur->val + left[0] + right[0];// 不偷cur，那么可以偷也可以不偷左右節點，則取較大的情況int val2 = max(left[0], left[1]) + max(right[0], right[1]);return {val2, val1};}
};