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  • LeetCode 112:Path Sum

    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.

     //利用深度优先搜索DFS,当搜索到的节点为叶子节点时。才推断总和是否等于给定的sum值
    class Solution {
    public:
    	bool dfs(TreeNode* node, int sum, int curSum){
    		if (node == NULL)
    			return false;
    		if (node->left == NULL && node->right == NULL)
    			return curSum + node->val == sum;
    
    		return dfs(node->left, sum, curSum + node->val) || dfs(node->right, sum, curSum + node->val);
    	}
    
    	bool hasPathSum(TreeNode* root, int sum) {
    		return dfs(root, sum, 0);
    	}
    };


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  • 原文地址:https://www.cnblogs.com/mthoutai/p/7262987.html
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