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leetcode_java/src/main/java/LeetCodeJava/Tree/BinaryTreeMaximumPathSum.java
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| package LeetCodeJava.Tree; | ||
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| // https://leetcode.com/problems/binary-tree-maximum-path-sum/description/ | ||
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| import LeetCodeJava.DataStructure.TreeNode; | ||
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| /** | ||
| * 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; | ||
| * } | ||
| * } | ||
| */ | ||
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| public class BinaryTreeMaximumPathSum { | ||
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| // V0 | ||
| // TODO : implement | ||
| // public int maxPathSum(TreeNode root) { | ||
| // | ||
| // return 0; | ||
| // } | ||
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| // V1 | ||
| // IDEA : DFS | ||
| // https://leetcode.com/problems/binary-tree-maximum-path-sum/solutions/4586190/beat-100-1/ | ||
| int max = Integer.MIN_VALUE; | ||
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| public int maxPath_1(TreeNode root) { | ||
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| if(root == null) return 0; | ||
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| int value = root.val; | ||
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| int left_sum = Math.max(maxPath_1(root.left),0); | ||
| int right_sum = Math.max(maxPath_1(root.right),0); | ||
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| max = Math.max(max, left_sum + right_sum + value); | ||
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| return Math.max(left_sum, right_sum) + value; | ||
| } | ||
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| public int maxPathSum_1(TreeNode root) { | ||
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| maxPath_1(root); | ||
| return max; | ||
| } | ||
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| // V2 | ||
| // IDEA : DFS | ||
| // https://leetcode.com/problems/binary-tree-maximum-path-sum/solutions/4538150/simple-java-solution-dfs/ | ||
| class INT { | ||
| int val; | ||
| } | ||
| public int maxPathSum_2(TreeNode root) { | ||
| INT maxPathLen = new INT(); | ||
| maxPathLen.val = Integer.MIN_VALUE; | ||
| dfs_2(root, maxPathLen); | ||
| return maxPathLen.val; | ||
| } | ||
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| int dfs_2(TreeNode root, INT maxLen) { | ||
| if(root == null) | ||
| return 0; | ||
| int left = Math.max(dfs_2(root.left, maxLen), 0); | ||
| int right = Math.max(dfs_2(root.right, maxLen), 0); | ||
| maxLen.val = Math.max(maxLen.val, root.val + left + right); | ||
| return root.val + Math.max(left, right); | ||
| } | ||
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| } |