c_cpp Path Sum http://oj.leetcode.com/problems/path-sum/

Posted 2021-05-14

/**
 * Definition for binary tree
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
    bool hasPathSum(TreeNode *root, int sum) {
        if(root == NULL){
            return false;
        }
        vector<TreeNode *> s;
        vector<bool> s_visit_left;
        vector<bool> s_visit_right;
        s.push_back(root);
        
        s_visit_left.push_back(false);
        s_visit_right.push_back(false);
        while(!s.empty()){
            if(s.back()->left == NULL && s.back()->right == NULL){
                int temp = 0;;
                for(int i = 0; i < s.size(); i++){
                    temp = temp + s[i]->val;
                }
                if(temp == sum){
                    return true;
                }
                s.pop_back();
                s_visit_left.pop_back();
                s_visit_right.pop_back();
            }
            else if(s.back()->left != NULL && !s_visit_left.back()){
                s_visit_left.back() = true;
                s.push_back(s.back()->left);
                s_visit_left.push_back(false);
                s_visit_right.push_back(false);
            }
            else if(s.back()->right != NULL && !s_visit_right.back()){
                s_visit_right.back() = true;
                s.push_back(s.back()->right);
                s_visit_left.push_back(false);
                s_visit_right.push_back(false);
            }
            else{
                s.pop_back();
                s_visit_left.pop_back();
                s_visit_right.pop_back();
            }
            
        }
        return false;
    }
};