Leetcode/leetcode653.cpp at main · ksaini-web/Leetcode · GitHub

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/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
 *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
 * };
 */
class Solution {
public:
unordered_set<int> st;

 bool solve(TreeNode* root , int k){

    if(root == NULL){
        return false;
    }

    if(st.find(k-root->val)!=st.end()){
        return true;
    }

    st.insert(root->val);

    return solve(root->left , k) || solve(root->right , k);
 }
    bool findTarget(TreeNode* root, int k) {

       return solve(root,k);


    }
};