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class Solution: | |
def medianSlidingWindow(self, nums: List[int], k: int) -> List[float]: | |
# Create an empty array to store your answer | |
res = [] | |
# Get the length of the nums array | |
n = len(nums) | |
# Slice the input array to get data from index 0 to index k | |
win_arr = nums[:k-1] |
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''' | |
Explanation: | |
- Note: Knowing which representation is the correct one for a particular number can be difficult. There are many possible ways of representing the number 120 for instance. | |
- So if num = 9, X and I are needed. Rule of roman numeral goes from largest to smallest. However, there are some special rules where the symbol with a smaller value can go before the symbol with a larger value. | |
- If there are no special rules, when num = 1500, | |
- We can divide 1500/M. i.e. 1500//1000 = 1. 1 tells us how many Ms in our final result. | |
- Then 1500 % 1000 = 500 | |
- 500 // 500 = 1. 1D in the final result |
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''' | |
Explanation: | |
- n = 19 --> 82 --> 68 --> 100 --> 1 | |
n // 10 = firstDigit | |
n % 10 = lastDigit | |
- n = 2 --> 4 --> 16 --> 37 --> 58 --> 89 --> 145 --> 42 --> 20 --> 4 | |
Since we've seen 4 before, then we know that the number is not happy. | |
Time Complexity: O(log n) - finding the sum square for a given number has a cost of O(logn) because we are processing each digit in the number, and the number of digits in a number is given by (log n): For n > 243, O(243 * 3 + log n + log log n + ....) = O(log n) |
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''' | |
Explanation: | |
- Intuitvely, we can find the possible areas for each pair of heights | |
- For each pair, we check the area by multiplying the width to the height without spill over. We need to consider the minimum height between the pair. | |
- However, can we reduce the number of times we find the possible areas for every pair of the heights which is caused by the minimum height in each pair? | |
- Yes, we can. We can have two pointers at both endpoints and perform the area of the ractangle. | |
- When the height is minimum for a left pointer, we can move to the pointer to the right and when the height is minimum for a right pointer, we move the pointer to the left to the right. This is done to look for the next possible maximum height. | |
- TC: O(n), SC: O(1) | |
''' |
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''' | |
Explanation: | |
- id passed in checkIn and checkOut: unique identifier to our customer | |
- Each customer can only be checked into a station one place at a time | |
1. Create a map called arrivals. key = id, value = tuple containing stationName and time --> (stationName, t) | |
2. To keep track of all previous travels between any two stations, we create another map called travels. key = stationNames separated by a delimiter, value = count, total --> [count, total] | |
Example: | |
Calls Arrivals Travels |
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''' | |
Explanation: | |
- We will have a recursive helper (flatten_helper) function that takes in the head pointer (curr = head, tail = head) | |
- While curr is not null, | |
- Here we can store curr, next and tail on the first node (head) | |
- If no child, | |
current = next and next will point to next of current | |
- If it has child, | |
We flatten the child. i.e. child_tail will be flatten_helper function called on child. Recursive function here | |
curr --> next = child |
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''' | |
Explanation: | |
- We have to pick equal number of A and B | |
Initially, | |
- Can we see if we can send all candidates to city A? | |
- Now, which of the candidates can we send to B? We will pick the candidate for which we gained the maximum (the most negative number) | |
10 + 30 + 400 + 30 | |
+10 +170 -350 -10 |
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''' | |
Explanation: | |
- Major steps to determine which candies to crush, | |
1. Check three or more candies to be crushed in rows | |
2. Check three or more candies to be crushed in columns | |
3. Dropping the candies | |
Steps 1 & 2: * This is an issue when considering columns --> [3,1,1,1,1,5] = [3,0,0,0,0,5] | |
Can we check for rows and columns simultaneously? Yes. We can use a slider of three at a time and check for the absolute values of the three integers. If the absolute values are the same, then we can change the integers to negative. | |
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''' | |
Explanation: | |
- deeedbbcccbdaa | |
[[d,1], [e,3]] | |
[[d,2]] | |
TC - O(2n) = O(n) where n is the size of the input string | |
SC - O(n) | |
''' |
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''' | |
Explanation I: Brute-force solution | |
- Convert the transactions to individual item of the valid data types and store it in an array. i.e. alice = string, 20 = integer, 800 = integer and mtv = string | |
- Loop through the new array and find where amount > 1000. Append that to result array and convert the transaction to a string splitting each item by comma | |
- Nested loop to check for same name, and if time difference is less than or equal to 60 and if different city, | |
- Append that to the res array and convert the transaction to a string splitting each item by comma | |
- TC - O(n-squared) | |
- SC - O(n) | |
''' |
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