Commit c9ffdc8

committed

Solve leetcode 1, 217, 409, and 88

1 parent 74bd35e commit c9ffdc8Copy full SHA for c9ffdc8

File tree

+95

-0

lines changed

+95

-0

lines changed

Lines changed: 21 additions & 0 deletions

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,21 @@`
	`1`	`+# Link: https://leetcode.com/problems/two-sum/`
	`2`	`+`
	`3`	`+def twoSum(nums, target):`
	`4`	`+ # key: Number that adds up to target`
	`5`	`+ # value: Index the number is at`
	`6`	`+ two_sum = {}`
	`7`	`+`
	`8`	`+ # Iterate through nums using indices b/c we need the indices`
	`9`	`+ # for the final ans`
	`10`	`+ for i in range(len(nums)):`
	`11`	`+ curr_num = nums[i]`
	`12`	`+ # Case 1: We found a pair that adds up to target`
	`13`	`+ if curr_num in two_sum:`
	`14`	`+ return [two_sum[curr_num], i]`
	`15`	`+ # Case 2: Add a new entry for the current number`
	`16`	`+ else:`
	`17`	`+ two_sum[target-curr_num] = i`
	`18`	`+`
	`19`	`+ # If we go through the entire for loop without returning`
	`20`	`+ # there's no valid answer`
	`21`	`+ return -1`

Lines changed: 17 additions & 0 deletions

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,17 @@`
	`1`	`+# Link: https://leetcode.com/problems/contains-duplicate/`
	`2`	`+`
	`3`	`+def containsDuplicate(nums):`
	`4`	`+ # A set keeping track of the numbers encountered so far`
	`5`	`+ num_seen = set()`
	`6`	`+`
	`7`	`+ for curr_num in nums:`
	`8`	`+ # Case 1: We have seen curr_num earlier on in nums`
	`9`	`+ if curr_num in num_seen:`
	`10`	`+ return True`
	`11`	`+ # Case 2: First encounter with curr_num`
	`12`	`+ else:`
	`13`	`+ num_seen.add(curr_num)`
	`14`	`+`
	`15`	`+ # If we go through the entire for loop without returning`
	`16`	`+ # there are no duplicates`
	`17`	`+ return False`

Lines changed: 34 additions & 0 deletions

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,34 @@`
	`1`	`+# Link: https://leetcode.com/problems/longest-palindrome/`
	`2`	`+`
	`3`	`+def longestPalindrome(s):`
	`4`	`+ # key: unique character`
	`5`	`+ # value: number of times said character occurs in s`
	`6`	`+ char_count = {}`
	`7`	`+`
	`8`	`+ # Populate the char_count dictionary`
	`9`	`+ for char in s:`
	`10`	`+ if char in char_count:`
	`11`	`+ char_count[char] += 1`
	`12`	`+ else:`
	`13`	`+ char_count[char] = 1`
	`14`	`+`
	`15`	`+ palindrome = 0 # Length of the longest palindrome`
	`16`	`+ odd = False # Whether there's at least one odd num occ char`
	`17`	`+`
	`18`	`+ for count in char_count.values():`
	`19`	`+ # Case 1: The current character occurs an odd number of times`
	`20`	`+ if count%2 != 0:`
	`21`	`+ odd = True # Set odd flag`
	`22`	`+ # Add an even number of those characters`
	`23`	`+ palindrome += (count-1)`
	`24`	`+ # Case 2: The current character occurs an even number of times`
	`25`	`+ else:`
	`26`	`+ palindrome += count`
	`27`	`+`
	`28`	`+ # If we encountered at least one oddly occuring character`
	`29`	`+ if odd:`
	`30`	`+ # Add 1 since you can have an odd number of chars in the middle`
	`31`	`+ # of the palindrome`
	`32`	`+ palindrome += 1`
	`33`	`+`
	`34`	`+ return palindrome`

Lines changed: 23 additions & 0 deletions

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,23 @@`
	`1`	`+# https://leetcode.com/problems/merge-sorted-array/`
	`2`	`+`
	`3`	`+def merge(nums1, m, nums2, n):`
	`4`	`+ # Iterate through both of the sorted arrays at the same time`
	`5`	`+ while m > 0 and n > 0:`
	`6`	`+ curr_1 = nums1[m-1]`
	`7`	`+ curr_2 = nums2[n-1]`
	`8`	`+`
	`9`	`+ if curr_1 >= curr_2:`
	`10`	`+ nums1[(m+n)-1] = curr_1`
	`11`	`+ m -= 1`
	`12`	`+ else: # curr_2 > curr_1`
	`13`	`+ nums1[(m+n)-1] = curr_2`
	`14`	`+ n -= 1`
	`15`	`+`
	`16`	`+ # If there are smaller elements left in nums2, copy them over.`
	`17`	`+ # No need to do this for leftover num1 elements, since we're`
	`18`	`+ # merging into nums1 and the elements will already be there.`
	`19`	`+ while n > 0:`
	`20`	`+ nums1[n-1] = nums2[n-1]`
	`21`	`+ n -= 1`
	`22`	`+`
	`23`	`+ return nums1`

Comments

(0)