Problems


November 20, 2022

Path with maximum probability

We can use Dijkstra's algorithm to find the shortest path from the start node to the end node. We will keep track of the probability of the shortest path from the start node to the current node. Then...

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November 20, 2022

Reverse prefix of word

We will iterate through the word and check if the current character is equal to the first character of the prefix. If it is, we will reverse the prefix and return the word. Time complexity:...

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November 20, 2022

Shopping offers

We can use DFS with memoization to solve this problem. We will keep track of the current state of the shopping list. Then we will iterate over each offer and we will check if the offer is valid. If...

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November 20, 2022

Widest vertical area between two points containing no points

We sort the points by x-coordinate, and find the maximum distance between two consecutive points. Time complexity: O(nlogn) Space complexity: O(n)

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November 19, 2022

Binary subarrays with sum

We can count the occurance of all the prefix sums. Then we will iterate through the prefix sums and check if the prefix sum minus the goal is in the hashmap. If yes, we will add the number of...

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November 19, 2022

Erect the fence

The problem is asking us to find the convex hull given a set of 2D points. Monotone Chain algorithm: Sort the points by x. (moving from left to right) Initialize a stack with the first 2 points....

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November 19, 2022

Maximum product after k increments

We will use a heap to keep track of the minimum element in the array. Then we will iterate k times and we will pop the minimum element from the heap and add 1 to it. We will push the new element back...

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November 19, 2022

Number of ways to split array

We will keep track of the left sum and right sum of the array. Then we iterate over each element until the last element, and we will check if the left sum is equal to the right sum. If yes, we will...

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November 18, 2022

First letter to appear twice

We will use a hashset to keep track of the letters we have seen. If we see a letter that is already in the hashset, we return it. Otherwise we add it to the hashset. Time complexity:...

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November 18, 2022

Frog position after t seconds

We will create a adjacency list to represent the graph. We will then use a DFS to traverse the graph. We will keep track of the number of children each node has. If the node has no children, we will...

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