Calculating the sum of each level in the tree

Question:


Given a binary tree with nodes containing integer values. Your algorithm should calculate the sum of values in each depth and returns sums.

Example:

          1
         /   \
       2     3
      /  \   /  \
    4   5 1    2

Output:  1, 5, 12

Answer

I don't remember where I saw this problem. If I remember I will update the labels.

I am still struggling with editing my layout. I would like to show the labels rather than the archive.
If you know how to do it, please, leave a comment. It will be a true win-win.

As the title indicates, it is a classic breast first search(BFS) problem. Using the BFS you can sum up the values and store in the output to return at the end of the problem.

Time complexity : $ (N)$
Space complexity:  $O(N)$

Here is the C++ source


UPDATE(2019-07-31): Solved the problem in python. I wrote the code quickly but got the test cases wrong. Took too long to find that bug after adding two print statements.


Practice statistics

7:00: to come up with an algorithm
13:00: to write up the code and test code (no bug)
07:00: to find the bug in the test code. (building the tree was wrong).

Total: 26:20

UPDATE(2022-06-14): solved again with no errors. Used python list as a queue.


04:32: for algorithm and pseudo code
08:18: to write up the code

Comments

Post a Comment

Popular posts from this blog

Planting flowers with no adjacent flower plots

Image
Problem Suppose you have a long flowerbed in which some of the plots are planted and some are not. However, flowers cannot be planted in adjacent plots - they would compete for water and both would die. Given a flowerbed (represented as an array containing booleans), return if a given number of new flowers can be planted in it without violating the no-adjacent-flowers rule  Sample inputs  Input: 1,0,0,0,0,0,1,0,0  3 => true  4 => false  Input: 1,0,0,1,0,0,1,0,0  1 => true  2 => false  input: 0  1 => true  2 => false  public boolean canPlaceFlowers(List flowerbed, int numberToPlace) {  // Implementation here  }
Read more
  Given an array of  intervals  where  intervals[i] = [start i , end i ] , merge all overlapping intervals, and return  an array of the non-overlapping intervals that cover all the intervals in the input . Example 1: Input: intervals = [[1,3],[2,6],[8,10],[15,18]] Output: [[1,6],[8,10],[15,18]] Explanation: Since intervals [1,3] and [2,6] overlap, merge them into [1,6]. Example 2: Input: intervals = [[1,4],[4,5]] Output: [[1,5]] Explanation: Intervals [1,4] and [4,5] are considered overlapping.   Constraints: 1 <= intervals.length <= 10 4 intervals[i].length == 2 0 <= start i <= end i <= 10 4
Read more

Find the maximum number of bomb that can be detonated

  Problem You are given a list of bombs. The range of a bomb is defined as the area where its effect can be felt. This area is in the shape of a circle with the center as the location of the bomb. The bombs are represented by a 0-indexed 2D integer array bombs where bombs[i] = [xi, yi, ri]. xi and yi denote the X-coordinate and Y-coordinate of the location of the ith bomb, whereas ri denotes the radius of its range. You may choose to detonate a single bomb. When a bomb is detonated, it will detonate all bombs that lie in its range.  These bombs will further detonate the bombs that lie in their ranges. Given the list of bombs, return the maximum number of bombs that can be detonated if you are allowed to detonate only one bomb. Input: bombs = [[2,1,3],[6,1,4]] Output: 2 Explanation: The above figure shows the positions and ranges of the 2 bombs. If we detonate the left bomb, the right bomb will not be affected. But if we detonate the right bomb, both bombs will be detonated. So...
Read more