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Recursion-687. Longest Univalue Path

时间:2018-01-13 11:06:21      阅读:153      评论:0      收藏:0      [点我收藏+]

标签:pass   des   repr   note   present   number   tun   color   example   

Given a binary tree, find the length of the longest path where each node in the path has the same value. This path may or may not pass through the root.

Note: The length of path between two nodes is represented by the number of edges between them.

Example 1:

Input:

              5
             /             4   5
           / \             1   1   5

 

Output:

2

 

Example 2:

Input:

              1
             /             4   5
           / \             4   4   5

 

Output:

2

 

Note: The given binary tree has not more than 10000 nodes. The height of the tree is not more than 1000.

 

class Solution {
public:
    int longestUnivaluePath(TreeNode* root) {
        int lup = 0;
        if (root) dfs(root, lup);
        return lup;
    }

private:
    int dfs(TreeNode* node, int& lup) {
        int l = node->left ? dfs(node->left, lup) : 0;
        int r = node->right ? dfs(node->right, lup) : 0;
        int resl = node->left && node->left->val == node->val ? l + 1 : 0;
        int resr = node->right && node->right->val == node->val ? r + 1 : 0;
        lup = max(lup, resl + resr);
        return max(resl, resr);
    }
};

 

Recursion-687. Longest Univalue Path

标签:pass   des   repr   note   present   number   tun   color   example   

原文地址:https://www.cnblogs.com/msymm/p/8278249.html

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