leetcode 34

python

Author: kyle8998

Diff for: README.md

@@ -38,6 +38,7 @@ Personal Practice Set - Doing One a Day (sometimes) in a Variety of Languages (M
 | 28 | Easy       | [Implement strStr()](leetcode/28-Easy-Implement-strStr/problem.md)                           | [C](leetcode/28-Easy-Implement-strStr/answer.c), [Python](leetcode/28-Easy-Implement-strStr/answer.py) |
 | 29 | Medium     | [Divide Two Integers](leetcode/29-Medium-Divide-Two-Integers/problem.md)                     | [Python](leetcode/29-Medium-Divide-Two-Integers/answer.py)        |
 | 33 | Medium     | [Search in Rotated Sorted Array](leetcode/33-Medium-Search-In-Rotated-Sorted-Array/problem.md) | [Python](leetcode/33-Medium-Search-In-Rotated-Sorted-Array/answer.py) |
+| 34 | Medium     | [Find First and Last Position of Element in Sorted Array](leetcode/34-Medium-Find-First-And-Last-Position-Of-Element-In-Sorted-Array/problem.md) | [Python](leetcode/34-Medium-Find-First-And-Last-Position-Of-Element-In-Sorted-Array/answer.py) |
 | 35 | Easy       | [Search Insert Position](leetcode/35-Easy-Search-Insert-Position/problem.md)                 | [Go](leetcode/35-Easy-Search-Insert-Position/answer.go), [Java](leetcode/35-Easy-Search-Insert-Position/answer.java), [JavaScript](leetcode/35-Easy-Search-Insert-Position/answer.js), [Scala](leetcode/35-Easy-Search-Insert-Position/answer.scala) |
 | 36 | Medium     | [Valid Sudoku](leetcode/36-Medium-Valid-Sudoku/problem.md)                                   | [Python](leetcode/36-Medium-Valid-Sudoku/answer.py)               |
 | 39 | Medium     | [Combination Sum](leetcode/39-Medium-Combination-Sum/problem.md)                             | [Python](leetcode/39-Medium-Combination-Sum/answer.py)            |

Diff for: leetcode/34-Medium-Find-First-And-Last-Position-Of-Element-In-Sorted-Array/answer.py

@@ -0,0 +1,69 @@
+#!/usr/bin/python3
+
+#------------------------------------------------------------------------------
+
+# This first solution is technically O(log(n)+k) where k is the number of occurances of target
+class Solution:
+    def searchRange(self, nums, target):
+        """
+        :type nums: List[int]
+        :type target: int
+        :rtype: List[int]
+        """
+        left = self.binarySearch(nums, target, 0, len(nums)-1)
+        if left == -1: return [-1, -1]
+        right = left
+        
+        while nums[left] == target and left > 0:
+            left -= 1
+        if nums[left] != target:
+            left += 1
+        while nums[right] == target and right < len(nums)-1:
+            right += 1
+        if nums[right] != target:
+            right -= 1
+        
+        return [left, right]
+    
+    def binarySearch(self, nums, target, left, right):
+        """
+        Binary Search for log(n) time
+        """
+        if right >= left:
+            mid = (left + right ) // 2
+
+            if nums[mid] == target:
+                return mid
+            elif nums[mid] > target:
+                return self.binarySearch(nums, target, left, mid-1)
+            else:
+                return self.binarySearch(nums, target, mid+1, right)
+        else:
+            return -1
+
+#------------------------------------------------------------------------------
+
+# This second solution is O(2log(n))
+class Solution:
+    def searchRange(self, nums, target):
+        def binarySearchLeft(A, x):
+            left, right = 0, len(A) - 1
+            while left <= right:
+                mid = (left + right) // 2
+                if x > A[mid]: left = mid + 1
+                else: right = mid - 1
+            return left
+
+        def binarySearchRight(A, x):
+            left, right = 0, len(A) - 1
+            while left <= right:
+                mid = (left + right) // 2
+                if x >= A[mid]: left = mid + 1
+                else: right = mid - 1
+            return right
+
+        left, right = binarySearchLeft(nums, target), binarySearchRight(nums, target)
+        return (left, right) if left <= right else [-1, -1]
+
+#------------------------------------------------------------------------------
+#Testing

Diff for: leetcode/34-Medium-Find-First-And-Last-Position-Of-Element-In-Sorted-Array/problem.md

@@ -0,0 +1,21 @@
+# Problem 34: Find First and Last Position of Element in Sorted Array
+
+#### Difficulty: Medium
+
+#### Problem
+
+Given an array of integers nums sorted in ascending order, find the starting and ending position of a given target value.
+
+Your algorithm's runtime complexity must be in the order of O(log n).
+
+If the target is not found in the array, return [-1, -1].
+
+#### Example
+
+<pre>
+
+Input: nums = [5,7,7,8,8,10], target = 8
+
+Output: [3,4]
+
+</pre>