标签：style blog class code java color
Given a binary tree and a sum, determine if the tree has a root-to-leaf path such that adding up all the values along the path equals the given sum.
For example:
Given the below binary tree
and sum = 22,
5
/ 4 8
/ / 11 13 4
/ \ 7 2 1
return true, as there exist a root-to-leaf
path 5->4->11->2 which sum is 22.
递归求解就可以。注意叶子结点条件是左右结点都为空。
1 /** 2 * Definition for binary tree 3 * struct TreeNode { 4 * int val; 5 * TreeNode *left; 6 * TreeNode *right; 7 * TreeNode(int x) : val(x), left(NULL), right(NULL) {} 8 * }; 9 */ 10 class Solution { 11 public: 12 bool hasPathSum(TreeNode *root, int sum) { 13 if (root == NULL) return false; 14 return recursive(root, sum, 0); 15 } 16 17 bool recursive(TreeNode *root, int sum, int cur) { 18 if (root == NULL) { 19 return false; 20 } 21 22 cur += root->val; 23 24 // leaf 25 if (root->left == NULL && root->right == NULL) { 26 return cur == sum; 27 } 28 29 bool res = recursive(root->left, sum, cur); 30 if (res) return true; 31 return recursive(root->right, sum, cur); 32 } 33 };
Given a binary tree and a sum, find all root-to-leaf paths where each path‘s sum equals the given sum.
For example:
Given the below binary tree
and sum = 22,
5
/ 4 8
/ / 11 13 4
/ \ / 7 2 5 1
return
[ [5,4,11,2], [5,8,4,5] ]
1 /** 2 * Definition for binary tree 3 * struct TreeNode { 4 * int val; 5 * TreeNode *left; 6 * TreeNode *right; 7 * TreeNode(int x) : val(x), left(NULL), right(NULL) {} 8 * }; 9 */ 10 class Solution { 11 public: 12 vector<vector<int> > pathSum(TreeNode *root, int sum) { 13 if (root == NULL) return ret; 14 vector<int> v; 15 16 int curSum = 0; 17 recursive(root, sum, curSum, v); 18 return ret; 19 } 20 21 void recursive(TreeNode *root, int sum, int curSum, vector<int> &v) { 22 if (root == NULL) return; 23 24 curSum += root->val; 25 v.push_back(root->val); 26 if (root->left == NULL && root->right == NULL) { 27 if (curSum == sum) { 28 ret.push_back(v); 29 } 30 } 31 recursive(root->left, sum, curSum, v); 32 recursive(root->right, sum, curSum, v); 33 v.pop_back(); 34 } 35 36 private: 37 vector<vector<int> > ret; 38 };
Leetcode | Path Sum I && II,布布扣,bubuko.com
标签：style blog class code java color
原文地址：http://www.cnblogs.com/linyx/p/3718379.html
