Interviewbit/PathSum.cpp at master · jayakrishna-g/Interviewbit · GitHub

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/*
Question:
Path Sum
Asked in:
Microsoft
Yahoo
Amazon
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.

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.

Return 0 / 1 ( 0 for false, 1 for true ) for this problem


 */

/**
 * Definition for binary tree
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
int Solution::hasPathSum(TreeNode* A, int B) {

    if(A==NULL)
    {
        return B==0;
    }
    if(A->left and A->right)
    return hasPathSum(A->left,B-A->val)||hasPathSum(A->right,B-A->val);
    if(A->left)
    return hasPathSum(A->left,B-A->val);
    if(A->right)
    return hasPathSum(A->right,B-A->val);
    return A->val==B;
}