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java的Deque

Leetcode 198. 打家劫舍

题目：198. 打家劫舍
解析：代码随想录解析

解题思路

偷：上上家的最大值加上这一家
不偷：上家的最大值

代码

class Solution {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 < dp.length; i++) {dp[i] = Math.max(dp[i-2] + nums[i], dp[i-1]);}return dp[dp.length-1];}
}//滚动数组
class Solution {public int rob(int[] nums) {if (nums == null || nums.length == 0)   return 0;if (nums.length == 1)   return nums[0];if (nums.length == 2)   return Math.max(nums[0], nums[1]);int []dp = new int[3];dp[0] = nums[0];dp[1] = Math.max(nums[0], nums[1]);for (int i = 2; i < nums.length; i++) {dp[2] = Math.max(dp[0] + nums[i], dp[1]);dp[0] = dp[1];dp[1] = dp[2];}return dp[2];}
}

总结

暂无

Leetcode 213. 打家劫舍 II

题目：213. 打家劫舍 II
解析：代码随想录解析

解题思路

去头去尾两种情况取最大值

代码

class Solution {public int rob(int[] nums) {if (nums == null || nums.length == 0)   return 0;if (nums.length == 1)   return nums[0];int result1 = robHouse(nums, 0, nums.length - 2);int result2 = robHouse(nums, 1, nums.length - 1);return Math.max(result1, result2);}private int robHouse(int[] nums, int begin, int end) {if (begin == end)return nums[begin];else if (begin + 1 == end)return Math.max(nums[begin], nums[begin + 1]);int []dp = new int[3];dp[0] = nums[begin];dp[1] = Math.max(nums[begin], nums[begin + 1]);for (int i = begin + 2; i <= end; i++) {dp[2] = Math.max(dp[1], dp[0] + nums[i]);dp[0] = dp[1];dp[1] = dp[2];}return dp[2];}
}

总结

暂无

Leetcode 337. 打家劫舍 III

题目：337. 打家劫舍 III
解析：代码随想录解析

解题思路

两种情况取最大值，当前节点偷两个孩子不偷；当前节点不透两个孩子偷和不偷的最大值。

代码

/*** Definition for a binary tree node.* public class TreeNode {*     int val;*     TreeNode left;*     TreeNode right;*     TreeNode() {}*     TreeNode(int val) { this.val = val; }*     TreeNode(int val, TreeNode left, TreeNode right) {*         this.val = val;*         this.left = left;*         this.right = right;*     }* }*/
class Solution {public int rob(TreeNode root) {int[] vals = robHouse(root);return Math.max(vals[0], vals[1]);}private int[] robHouse(TreeNode root) {int[] res = new int[2];if (root == null)return res;int[] left = robHouse(root.left);int[] right = robHouse(root.right);//0表示偷，1表示不偷res[0] = root.val + left[1] + right[1];res[1] = Math.max(left[0], left[1]) + Math.max(right[0], right[1]);return res;}
}

总结

暂无