Leetcode-Solutions/437-path-sum-iii.cpp at main · aghersidev/Leetcode-Solutions · 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:
    int full(TreeNode* root, long targetSum) {
        int sum=0;
        if (root->val == targetSum) sum++;
        if (root->left)
        sum += full(root->left, targetSum - root->val);
        if (root->right)
        sum += full(root->right, targetSum - root->val);
        return sum;
    }

    int pathSum(TreeNode* root, int targetSum) {
        if (!root) return 0;
        int sum = 0;
        if (root->left) {
            sum += pathSum(root->left, targetSum);
            sum += full(root->left, targetSum - root->val);
        }
        if (root->right) {
            sum += pathSum(root->right, targetSum);
            sum += full(root->right, targetSum- root->val);
        }
        if (root->val == targetSum) sum++;
        return sum;
    }
};