Problems
August 7, 2022
Non overlapping intervals
First we will sort the intervals. Then we will iterate through all the intervals, compare if we have any collision between 2 consecutive interval, if yes, then we will count that, then after the...
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Minimum interval to include each query
We will keep track of the smallest interval for each query in a min heap, so whenever we pop something from the heap, it's always the smallest number. And then we put that smallest number in our...
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Detect squares
We will keep track of each elements in a list and their respective points count in a hashmap. Whenever we add a point, we increment the points count and also add the point in points list. We we...
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Rotate image
We will save the topleft to a temporary variable and then move the bottom left to top left, then move the bottom right to bottom left and move the top right to bottom right and then finally move the...
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Set matrix zeroes
First we will go through the whole matrix, if we find a zero and we append it's row position to a rows to zero list and column position to columns to zero list. Then We go through each row from rows...
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Spiral matrix
First we will determine the value of left, right, top and bottom. Then we append the top row to our result, then right column, then bottom row in reverse order and then left column in reverse order....
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Find median from data stream
We will use a min heap and a max heap to calculate the median. The small heap will be a max heap and large heap will be a min heap. All the elements of the small heap will be smaller than large heap....
ReadAugust 6, 2022
Serialize and deserialize binary tree
For serialize the tree, we will traverse the tree in preorder and whenever we hit a null node, we put a # character there. Then we join each character with a comma delimeter and return...
August 6, 2022
Merge k sorted lists
We can merge 2 sorted list with O(n) time complexity. Now we can go through the lists, and merge it one by one, this will be a O(n^2) operation. But if we merge every 2 list...
August 6, 2022
Reverse nodes in k group
We will create a helper funtion to get the kths item of the list. Then as we go through the whole list, we will take kth item, reverse it in place and move forward till the end of the ;list. Time...
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