diff --git a/problems/0337.打家劫舍III.md b/problems/0337.打家劫舍III.md index 50b06e22..20eea817 100644 --- a/problems/0337.打家劫舍III.md +++ b/problems/0337.打家劫舍III.md @@ -218,7 +218,72 @@ public: Java: +```Java +class Solution { + // 1.递归去偷,超时 + public int rob(TreeNode root) { + if (root == null) + return 0; + int money = root.val; + if (root.left != null) { + money += rob(root.left.left) + rob(root.left.right); + } + if (root.right != null) { + money += rob(root.right.left) + rob(root.right.right); + } + return Math.max(money, rob(root.left) + rob(root.right)); + } + // 2.递归去偷,记录状态 + // 执行用时:3 ms , 在所有 Java 提交中击败了 56.24% 的用户 + public int rob1(TreeNode root) { + Map memo = new HashMap<>(); + return robAction(root, memo); + } + + int robAction(TreeNode root, Map memo) { + if (root == null) + return 0; + if (memo.containsKey(root)) + return memo.get(root); + int money = root.val; + if (root.left != null) { + money += robAction(root.left.left, memo) + robAction(root.left.right, memo); + } + if (root.right != null) { + money += robAction(root.right.left, memo) + robAction(root.right.right, memo); + } + int res = Math.max(money, robAction(root.left, memo) + robAction(root.right, memo)); + memo.put(root, res); + return res; + } + + // 3.状态标记递归 + // 执行用时:0 ms , 在所有 Java 提交中击败了 100% 的用户 + // 不偷:Max(左孩子不偷,左孩子偷) + Max(又孩子不偷,右孩子偷) + // root[0] = Math.max(rob(root.left)[0], rob(root.left)[1]) + + // Math.max(rob(root.right)[0], rob(root.right)[1]) + // 偷:左孩子不偷+ 右孩子不偷 + 当前节点偷 + // root[1] = rob(root.left)[0] + rob(root.right)[0] + root.val; + public int rob3(TreeNode root) { + int[] res = robAction1(root); + return Math.max(res[0], res[1]); + } + + int[] robAction1(TreeNode root) { + int res[] = new int[2]; + if (root == null) + return res; + + int[] left = robAction1(root.left); + int[] right = robAction1(root.right); + + res[0] = Math.max(left[0], left[1]) + Math.max(right[0], right[1]); + res[1] = root.val + left[0] + right[0]; + return res; + } +} +``` Python: