404 Sum of Left Leaves 左葉子之和
阿新 • • 發佈:2018-04-16
AR tree etc 二叉 ble roo bsp true desc
計算給定二叉樹的所有左葉子之和。
示例:
3
/ \
9 20
/ \
15 7
在這個二叉樹中,有兩個左葉子,分別是 9 和 15,所以返回 24。
詳見:https://leetcode.com/problems/sum-of-left-leaves/description/
C++:
方法一:
/** * Definition for a binary tree node. * struct TreeNode { * int val; * TreeNode *left; * TreeNode *right; * TreeNode(int x) : val(x), left(NULL), right(NULL) {} * }; */ class Solution { public: int sumOfLeftLeaves(TreeNode* root) { if(!root||!root->left&&!root->right) { return 0; } int res=0; queue<TreeNode*> que; que.push(root); while(!que.empty()) { root=que.front(); que.pop(); if(root->left&&!root->left->left&&!root->left->right) { res+=root->left->val; } if(root->left) { que.push(root->left); } if(root->right) { que.push(root->right); } } return res; } };
方法二:
/** * Definition for a binary tree node. * struct TreeNode { * int val; * TreeNode *left; * TreeNode *right; * TreeNode(int x) : val(x), left(NULL), right(NULL) {} * }; */ class Solution { public: int sumOfLeftLeaves(TreeNode* root) { if(!root) { return 0; } if(root->left&&!root->left->left&&!root->left->right) { return root->left->val+sumOfLeftLeaves(root->right); } return sumOfLeftLeaves(root->left)+sumOfLeftLeaves(root->right); } };
參考:https://www.cnblogs.com/grandyang/p/5923559.html
404 Sum of Left Leaves 左葉子之和