2022-09-24 Daily-Challenge

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Today I have done leetcode's September LeetCoding Challenge with cpp.

September LeetCoding Challenge 24

Description

Path Sum II

Given the root of a binary tree and an integer targetSum, return all root-to-leaf paths where the sum of the node values in the path equals targetSum. Each path should be returned as a list of the node values, not node references.

A root-to-leaf path is a path starting from the root and ending at any leaf node. A leaf is a node with no children.

Example 1:

img

Input: root = [5,4,8,11,null,13,4,7,2,null,null,5,1], targetSum = 22
Output: [[5,4,11,2],[5,8,4,5]]
Explanation: There are two paths whose sum equals targetSum:
5 + 4 + 11 + 2 = 22
5 + 8 + 4 + 5 = 22

Example 2:

img

Input: root = [1,2,3], targetSum = 5
Output: []

Example 3:

Input: root = [1,2], targetSum = 0
Output: []

Constraints:

  • The number of nodes in the tree is in the range [0, 5000].
  • -1000 <= Node.val <= 1000
  • -1000 <= targetSum <= 1000

Solution

class Solution {
  void solve(
    vector<vector<int>> &answer,
    vector<int> &container,
    TreeNode *root,
    int rest
  ) {
    if(!root) return;
    container.push_back(root->val);
    rest -= root->val;
    if(!rest && !root->left && !root->right) {
      answer.push_back(container);
    } else {
      solve(answer, container, root->left, rest);
      solve(answer, container, root->right, rest);
    }
    container.pop_back();
  }
public:
  vector<vector<int>> pathSum(TreeNode* root, int targetSum) {
    vector<vector<int>> answer;
    vector<int> temp;
    solve(answer, temp, root, targetSum);
    return move(answer);
  }
};

// Accepted
// 115/115 cases passed (0 ms)
// Your runtime beats 100 % of cpp submissions
// Your memory usage beats 81.42 % of cpp submissions (19.8 MB)
Algorithm