LeetCode124 Binary Tree Maximum Path Sum

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详细见：leetcode.com/problems/binary-tree-maximum-path-sum

Java Solution: github

package leetcode;import tools.TreeNode辅助.TreeNode;/*    Given a binary tree, find the maximum path sum.For this problem, a path is defined as any sequence of nodes from some starting node to any node in the tree  along the parent-child connections.  The path does not need to go through the root.For example:Given the below binary tree,       1      / \     2   3Return 6. *//** * @author      zxwtry * @email       zxwtry@qq.com * @project     OJ * @package     leetcode * @file        P124_BinaryTreeMaximumPathSum.java * @type        P124_BinaryTreeMaximumPathSum * @date        2017年5月7日 下午10:02:15 * @details     Solution: AC 3ms 19.84% */public class P124_BinaryTreeMaximumPathSum {static class Solution {    public int maxPathSum(TreeNode root) {        if (root == null) return 0;        int[] ans = {Integer.MIN_VALUE};    search(root, ans);        return ans[0];    }private int search(TreeNode root, int[] ans) {    if (root == null) return 0;    int lv = Math.max(0, search(root.left, ans));    int rv = Math.max(0, search(root.right, ans));    ans[0] = Math.max(ans[0], lv+rv+root.val);    return Math.max(lv, rv) + root.val;}}}

C Solution: github

/*    url: leetcode.com/problems/binary-tree-maximum-path-sum    AC 15ms 59.26%*/#include <stdio.h>#include <stdlib.h>#include <limits.h>struct TreeNode {    int val;    struct TreeNode *left;    struct TreeNode *right;};typedef struct TreeNode stn;typedef struct TreeNode * ptn;int _max(int a, int b) {    return a < b ? b : a;}int search(ptn n, int* m) {    int lv = 0, rv = 0;    if (n == NULL) return 0;    lv = search(n->left, m);    rv = search(n->right, m);    *m = _max(*m, lv + rv + n->val);    return _max(_max(_max(lv, rv), 0) + n->val, 0);}int maxPathSum(ptn n) {    int m = INT_MIN;    if (n == NULL) return 0;    search(n, &m);        return m;}

Python Solution: github

#coding=utf-8'''    url: leetcode.com/problems/binary-tree-maximum-path-sum    @author:     zxwtry    @email:      zxwtry@qq.com    @date:       2017年5月10日    @details:    Solution:  222ms 16.58%'''class TreeNode(object):    def __init__(self, x):        self.val = x        self.left = None        self.right = Noneclass Solution(object):    def search(self, n, ans):        if n == None: return 0        lv = max(self.search(n.left, ans), 0)        rv = max(self.search(n.right, ans), 0)        ans[0] = max(ans[0], lv+rv+n.val)        return max(lv, rv) + n.val            def maxPathSum(self, n):        """        :type n: TreeNode        :rtype: int        """        ans = [-(1 << 31)]        self.search(n, ans)        return 0 if n == None else ans[0]    if __name__ == "__main__":    t0 = TreeNode(-1)    print(Solution().maxPathSum(t0))    print(Solution().maxPathSum(None))

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