Commit a40960d

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Merge pull request #19 from mihirs16/master

added leetcode questions

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	`1`	`+# three sum \| leetcode 15 \| https://leetcode.com/problems/3sum/`
	`2`	`+# - sorted; nested loop; outer loop for first element`
	`3`	`+# - inner loop for two sum on rest of list`
	`4`	`+# - avoid duplicates by shifting window till last occurrence`
	`5`	`+`
	`6`	`+class Solution:`
	`7`	`+ def threeSum(self, nums: list[int]) -> list[list[int]]:`
	`8`	`+ nums.sort()`
	`9`	`+ N = len(nums)`
	`10`	`+ triplets = []`
	`11`	`+ for i in range(N):`
	`12`	`+ if i > 0 and nums[i] == nums[i - 1]:`
	`13`	`+ continue`
	`14`	`+`
	`15`	`+ ptrL = i + 1`
	`16`	`+ ptrR = N - 1`
	`17`	`+ while ptrL < ptrR:`
	`18`	`+ s = nums[i] + nums[ptrL] + nums[ptrR]`
	`19`	`+ if s > 0:`
	`20`	`+ ptrR -= 1`
	`21`	`+ elif s < 0:`
	`22`	`+ ptrL += 1`
	`23`	`+ else:`
	`24`	`+ triplets.append([nums[i], nums[ptrL], nums[ptrR]])`
	`25`	`+ ptrL += 1`
	`26`	`+ while nums[ptrL] == nums[ptrL - 1] and ptrL < ptrR:`
	`27`	`+ ptrL += 1`
	`28`	`+`
	`29`	`+ return triplets`

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	`1`	`+# two sum II - input array is sorted \| leetcode 167 \| https://leetcode.com/problems/two-sum-ii-input-array-is-sorted`
	`2`	`+# use two pointers on sorted array; if sum > target slide window left, else slide window right`
	`3`	`+`
	`4`	`+class Solution:`
	`5`	`+ def twoSum(self, numbers: list[int], target: int) -> list[int]:`
	`6`	`+ ptrL = 0`
	`7`	`+ ptrR = 1`
	`8`	`+ N = len(numbers)`
	`9`	`+`
	`10`	`+ while ptrR < N:`
	`11`	`+ s = numbers[ptrR] + numbers[ptrL]`
	`12`	`+ if s == target:`
	`13`	`+ return [ptrL + 1, ptrR + 1]`
	`14`	`+ elif s < target:`
	`15`	`+ ptrL += 1`
	`16`	`+ ptrR += 1`
	`17`	`+ else:`
	`18`	`+ ptrL -= 1`
	`19`	`+`
	`20`	`+ # unreachable for testcases with exactly one solution`
	`21`	`+ return [-1, -1]`

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	`1`	`+# naming a company \| leetcode 2306 \| https://leetcode.com/problems/naming-a-company`
	`2`	`+# bucket by starting character to make it n(26^2.n) and compare each set with each other`
	`3`	`+`
	`4`	`+class Solution:`
	`5`	`+ def distinctNames(self, ideas: list[str]) -> int:`
	`6`	`+ buckets = dict()`
	`7`	`+ num_distinct = 0`
	`8`	`+`
	`9`	`+ for idea in ideas:`
	`10`	`+ if buckets.get(idea[0]) is None:`
	`11`	`+ buckets[idea[0]] = {idea[1:]}`
	`12`	`+ else:`
	`13`	`+ buckets[idea[0]].add(idea[1:])`
	`14`	`+`
	`15`	`+ for prefix_i, suffix_i in buckets.items():`
	`16`	`+ for prefix_j, suffix_j in buckets.items():`
	`17`	`+ if prefix_i == prefix_j:`
	`18`	`+ continue`
	`19`	`+ common = len(suffix_i & suffix_j)`
	`20`	`+ common_i = len(suffix_i) - common`
	`21`	`+ common_j = len(suffix_j) - common`
	`22`	`+ num_distinct += common_i * common_j`
	`23`	`+`
	`24`	`+ return num_distinct`

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