The. Path Sum (Tree; DFS)

Given a binary tree and a sum, determine if the tree has a root-to-leaf path such this adding up all the values along the Path equals the given sum.

For example:
Given the below binary tree sum = 22 and,

              5             /             4   8           /   /           /  4         /  \              7    2      1

structTreeNode {intVal; TreeNode*Left ; TreeNode*Right ; TreeNode (intx): Val (x), left (null), right (null) {}};classSolution { Public:    BOOLHaspathsum (TreeNode *root,intsum) {        //Start Typing your/C + + solution below//Do not write int main () function        if(!root)return false; Flag=false; Target=sum; Preorder (Root,0); returnFlag; }    voidPreorder (treenode* node,intsum) {Sum= Node->val + sum;//before recursion, add the current node        if(node->Left ) {Preorder (node-left,sum); }        if(node->Right ) {Preorder (node-right,sum); }        if(!node->left &&!node->right && sum = = target)//recursive end condition: to the leaf node{flag=true; }    }Private:    BOOLFlag; inttarget;};

The. Path Sum (Tree; DFS)