note0979.md

Leetcode (979. Distribute Coins in Binary Tree)[https://leetcode.com/problems/distribute-coins-in-binary-tree/]

• Type: binary tree
• Approach:
  • dfs + bottom-up
  • For each node, return cur_node.val+left+right-1, for we have totally cur_node.val+left+right coins at the current node, we need to do (total coins - 1) numbers of operations to distribute coins; as for result, we accumulatively add abs(left)+abs(right) to the result.
• Boundary and results:
  • If not node, return 0
• Complexity:
  • Time: O(n)
  • Space: O(1)