Merge pull request #17 from tiationg-kho/update

update

Author: tiationg-kho

README.md

@@ -209,24 +209,24 @@ Pattern500 is inspired by Blind 75 and Grind 75's classic problem selection. Pat
 | 195 | | [472. Concatenated Words](https://leetcode.com/problems/concatenated-words/) | [G]trie | perform dfs inside trie | [Python]([G]trie/[G]trie/472-concatenated-words.py) |
 | 196 | | [642. Design Search Autocomplete System](https://leetcode.com/problems/design-search-autocomplete-system/) | [G]trie | perform dfs inside trie | [Python]([G]trie/[G]trie/642-design-search-autocomplete-system.py) |
 | 197 | | [array]([H]array/array.md) | [H]array | | |
-| 198 | O | [XX]()  | [X]XX  | XX  | [Python]()  |
-| 199 | O | [XX]()  | [X]XX  | XX   | [Python]()  |
-| 200 | O | [XX]()  | [X]XX  | XX   | [Python]()  |
-| 201 | O | [XX]()  | [X]XX  | XX   | [Python]()  |
-| 202 | O | [XX]()  | [X]XX  | XX   | [Python]()  |
-| 203 | O | [XX]()  | [X]XX  | XX   | [Python]()  |
-| 204 | O | [XX]()   | [X]XX  | XX   | [Python]()  |
-| 205 | O | [XX]()   | [X]XX  | XX   | [Python]()  |
-| 206 | O | [XX]()   | [X]XX  | XX   | [Python]()  |
-| 207 | O | [XX]()   | [X]XX  | XX   | [Python]()  |
-| 208 | O | [XX]()  | [X]XX  | XX   | [Python]()  |
-| 209 | O | [XX]()   | [X]XX  | XX   | [Python]()  |
-| 210 | O | [XX]()  | [X]XX  | XX   | [Python]()  |
-| 211 | O | [XX]()  | [X]XX  | XX   | [Python]()  |
-| 212 | O | [XX]()   | [X]XX  | XX  | [Python]()  |
-| 213 | O | [XX]()  | [X]XX  | XX   | [Python]()  |
-| 214 | O | [XX]()  | [X]XX  | XX   | [Python]()  |
-| 215 | O | [XX]()  | [X]XX  | XX   | [Python]()  |
+| 198 |  | [243. Shortest Word Distance](https://leetcode.com/problems/shortest-word-distance/) | [H]array | traverse | [Python]([H]array/[H]array/243-shortest-word-distance.py) |
+| 199 | O | [169. Majority Element](https://leetcode.com/problems/majority-element/) | [H]array | use boyer moore vote algorithm | [Python]([H]array/[H]array/169-majority-element.py) |
+| 200 |  | [229. Majority Element II](https://leetcode.com/problems/majority-element-ii/) | [H]array | use boyer moore vote algorithm | [Python]([H]array/[H]array/229-majority-element-ii.py) |
+| 201 | O | [189. Rotate Array](https://leetcode.com/problems/rotate-array/) | [H]array | use reverse technique | [Python]([H]array/[H]array/189-rotate-array.py) |
+| 202 | O | [362. Design Hit Counter](https://leetcode.com/problems/design-hit-counter/) | [H]array | use circular array | [Python]([H]array/[H]array/362-design-hit-counter.py) |
+| 203 | O | [41. First Missing Positive](https://leetcode.com/problems/first-missing-positive/) | [H]array | specific range array (cyclic sort) | [Python]([H]array/[H]array/41-first-missing-positive.py) |
+| 204 |  | [442. Find All Duplicates in an Array](https://leetcode.com/problems/find-all-duplicates-in-an-array/) | [H]array | specific range array (cyclic sort) | [Python]([H]array/[H]array/442-find-all-duplicates-in-an-array.py) |
+| 205 |  | [448. Find All Numbers Disappeared in an Array](https://leetcode.com/problems/find-all-numbers-disappeared-in-an-array/) | [H]array | specific range array (cyclic sort) | [Python]([H]array/[H]array/448-find-all-numbers-disappeared-in-an-array.py) |
+| 206 | O | [287. Find the Duplicate Number](https://leetcode.com/problems/find-the-duplicate-number/) | [H]array | specific range array (cycle detection) | [Python]([H]array/[H]array/287-find-the-duplicate-number.py) |
+| 207 |  | [845. Longest Mountain in Array](https://leetcode.com/problems/longest-mountain-in-array/) | [H]array | use finite state machine | [Python]([H]array/[H]array/845-longest-mountain-in-array.py) |
+| 208 |  | [370. Range Addition](https://leetcode.com/problems/range-addition/) | [H]array | use difference array | [Python]([H]array/[H]array/370-range-addition.py) |
+| 209 |  | [849. Maximize Distance to Closest Person](https://leetcode.com/problems/maximize-distance-to-closest-person/) | [H]array | count continuous elements | [Python]([H]array/[H]array/849-maximize-distance-to-closest-person.py) |
+| 210 |  | [384. Shuffle an Array](https://leetcode.com/problems/shuffle-an-array/) | [H]array | use knuth shuffle | [Python]([H]array/[H]array/384-shuffle-an-array.py) |
+| 211 |  | [398. Random Pick Index](https://leetcode.com/problems/random-pick-index/) | [H]array | use reservoir sampling | [Python]([H]array/[H]array/398-random-pick-index.py) |
+| 212 |  | [1535. Find the Winner of an Array Game](https://leetcode.com/problems/find-the-winner-of-an-array-game/) | [H]array | simulation | [Python]([H]array/[H]array/1535-find-the-winner-of-an-array-game.py) |
+| 213 |  | [280. Wiggle Sort](https://leetcode.com/problems/wiggle-sort/) | [H]array | use swap | [Python]([H]array/[H]array/280-wiggle-sort.py) |
+| 214 |  | [1472. Design Browser History](https://leetcode.com/problems/design-browser-history/) | [H]array | maintain array's range dynamically | [Python]([H]array/[H]array/1472-design-browser-history.py) |
+| 215 |  | [163. Missing Ranges](https://leetcode.com/problems/missing-ranges/) | [H]array | pre-process the array | [Python]([H]array/[H]array/163-missing-ranges.py) |
 | 216 | O | [XX]() | [X]XX | XX | [Python]() |
 | 217 | O | [XX]() | [X]XX | XX | [Python]() |
 | 218 | O | [XX]() | [X]XX | XX | [Python]() |

[H]array/[H]array/1472-design-browser-history.py

@@ -0,0 +1,43 @@
+class BrowserHistory:
+
+ def __init__(self, homepage: str):
+ self.pages = [homepage]
+ self.start = 0
+ self.cur = 0
+ self.end = 0
+ 
+ def visit(self, url: str) -> None:
+ if self.cur + 1 == len(self.pages):
+ self.pages.append(url)
+ self.cur += 1
+ self.end = self.cur
+ else:
+ self.pages[self.cur + 1] = url
+ self.cur += 1
+ self.end = self.cur
+
+ def back(self, steps: int) -> str:
+ if self.cur - steps >= self.start:
+ self.cur -= steps
+ return self.pages[self.cur]
+ else:
+ self.cur = self.start
+ return self.pages[self.cur]
+
+ def forward(self, steps: int) -> str:
+ if self.cur + steps <= self.end:
+ self.cur += steps
+ return self.pages[self.cur]
+ else:
+ self.cur = self.end
+ return self.pages[self.cur]
+
+# Your BrowserHistory object will be instantiated and called as such:
+# obj = BrowserHistory(homepage)
+# obj.visit(url)
+# param_2 = obj.back(steps)
+# param_3 = obj.forward(steps)
+
+# time O(1) for all
+# space O(n)
+# using array and maintain array's range dynamically

[H]array/[H]array/1535-find-the-winner-of-an-array-game.py

@@ -0,0 +1,29 @@
+class Solution:
+ def getWinner(self, arr: List[int], k: int) -> int:
+ max_num = max(arr)
+ 
+ cur = None
+ count = 0
+ for i, num in enumerate(arr):
+ if num == max_num:
+ cur = num
+ break
+ if not cur:
+ cur = num
+ elif cur < num:
+ cur = num
+ count = 1
+ else:
+ count += 1
+ if count == k:
+ break
+ return cur
+ 
+# time O(n)
+# space O(1)
+# using array and simulation
+'''
+1. we can use queue to simulate the game
+2. but actually if we met max num, max num will always be res
+3. so, we do not need to consider element behind max num (involves the elements which were moved to end)
+'''

[H]array/[H]array/163-missing-ranges.py

@@ -0,0 +1,14 @@
+class Solution:
+ def findMissingRanges(self, nums: List[int], lower: int, upper: int) -> List[List[int]]:
+ nums = [lower - 1] + nums + [upper + 1]
+ res = []
+ for i in range(1, len(nums)):
+ prev = nums[i - 1]
+ cur = nums[i]
+ if cur - prev >= 2:
+ res.append([prev + 1, cur - 1])
+ return res
+ 
+# time O(n)
+# space O(n)
+# using array and pre-process

[H]array/[H]array/169-majority-element.py

@@ -0,0 +1,19 @@
+class Solution:
+ def majorityElement(self, nums: List[int]) -> int:
+ cand = None
+ vote = 0
+ for num in nums:
+ if num == cand:
+ vote += 1
+ elif cand == None:
+ cand = num
+ vote = 1
+ else:
+ vote -= 1
+ if vote == 0:
+ cand = None
+ return cand
+
+# time O(n)
+# space O(1)
+# using array and boyer moore vote algorithm

[H]array/[H]array/189-rotate-array.py

@@ -0,0 +1,24 @@
+class Solution:
+ def rotate(self, nums: List[int], k: int) -> None:
+ """
+ Do not return anything, modify nums in-place instead.
+ """
+ 
+ def helper(left, right):
+ while left < right:
+ nums[left], nums[right] = nums[right], nums[left]
+ left += 1
+ right -= 1
+ 
+ k %= len(nums)
+ helper(0, len(nums) - 1)
+ helper(0, k - 1)
+ helper(k, len(nums) - 1)
+ 
+# time O(n)
+# space O(1)
+# using array and reverse technique
+'''
+1. after rotate, can divide array into two part
+2. rotate them again
+'''